Or just use PR Spitfires and Mosquitoes.
But in the low to medium altitude Tactical Reconnaissance role the RAF did not, if they could avoid it, use their special build, dedicated PR Spitfires and Mosquitoes in that role.
That is why with the declining number of Allison engine Mustangs available to the RAF 2TAF Tac/R Squadrons you end up with Spitfire Vs fitted with an oblique camera and a low altitude rated Merlin equipping a couple of the Tac/R Squadrons in 1944; the Spitfire FR.IX as an interim type in 1944; the Hawker Typhoon FR.1b, and then eventually the Spitfire FR.XIV - again with engine optimised for low to medium altitude use. The problem with all those replacement and interim types when their use in the TacR role was evaluated, was that they usually did not meet one or more of the identified key criteria. That might be in relation to the number and types of cameras able to be carried and the types of photography they could conduct; range (importantly without use of drop tanks or external fuel to extend range); low to medium level performance (which also took into account engine performance and engine and airframe vibration at operational altitudes and airspeeds); and ability to operate from ALGs in a wide range of conditions (landing and take-off distances, rough strips, cross winds, in field maintenance). Added in their as well was armament, sufficient for self protection and suppression of enemy defensive flak in some instances as well as ability to take out targets of opportunity if it did not jeopardise the primary task of the aircraft, being reconnaissance and getting either the visual report from the pilot or the photographs back to base.
Two different roles and requirements within the RAF Reconnaissance Wings in 2TAF supporting the Army Groups as they were set up from late 1943 and going forward.
Usually one Squadron of high level PR types, originally to be either Spitfire PR.XI or PR Mosquito - the idea for the use of the Mosquito was soon dropped due to the planned 'mobile' nature of the Wings, the larger sized ALGs and additional support requirements for the Mosquito vs the Spitfire PR.XI. To be used to obtain 'strategic' photographic reconnaisance coverage for the Army, usually large scale coverage of the front line and areas extending back from the front line on both sides of the line. A large focus on obtaining coverage to develop up to date maps and identify key enemy pressure point and nodes including supply centres,
Then there would be two or three low to medium level Tac/R Squadrons initially intended to be equipped with Allison engine Mustangs, all aircraft to be fitted with oblique cameras, and a percentage of those also to be fitted with a vertical camera, eventually intending all to have oblique and vertical camera carrying capability. These to provide the low level tactical coverage, more immediately the front line and immediate areas behind the frontline, obtaining photography with greater detail of specific features. Part of the use of the low level oblique photography was to obtain photography that could be used to plan and brief operations by Army units, providing a point of view usable by advancing units that they didn't get from the high level 'strategic' PR coverage. In addition to the Tactical Photographic Reconnaissance, they also did Artillery Reconnaissance - directing artillery; contact patrols in conjunction with contact cars with forward Army units where they could be requested to investigate areas to the immediate front of the Army unit. They also did a lot of post strike reconnaissance after artillery barrages and after attacks on enemy positions or locations by the medium bombers of 2TAF/2Group as well as post strike of attacks by rocket carrying Typhoons or fighter bomber Typhoons or Spitfires - very immediate where they would often 'tag along' just behind the attacking formations and have the photos back being processed before the attacking aircraft were back at base.
One of the issues the 2TAF Reconnaissance WIngs encountered after the invasion was getting space on the ALGs, and then as the advance occurred, getting space on ALGs relatively close to the front line. There was an issue where the supporting fighter/fighter-bomber units would get space on ALGs relatively close to the front so they could generate the maximum number of sorties over the front line as quickly as possible - proximity to the front. The Recce Wings were then fitted in as an afterthought, which meant at certain stages of the campaign they were operating from bases well back from the front, which then limited some types eg the Spitfire FR.IX and Typhoon FR.1b in the time they could spend over the front and distance beyond the front they could cover due to their reduced range compared to the Mustang. As a result, a larger percentage of the required tasking fell onto the Mustang units with the result that they used up their airframes, engines, etc a lot quicker than originally anticipated. There were also instances where the Recce Wings were moved into ALGs where the orientation of the available runways regularly made them unusable by the Spitfires as they were out of their crosswind limits (even with wartime allowances), or the quality of the ALG runway was so poor that the units with Spitfires had a significantly higher rate of take off and landing accidents whilst at those ALGs, compared to the units with the Mustangs or Typhoons. So again, more demand on the reducing number of available Allison engine Mustang airframes they had left.
After VE-Day, with the downsizing of the RAF and establishment of BAFO, they disbanded a lot of Squadrons and created 'composite' Recce Squadrons in the Army Co-operation/Support role, comprising two flights of low to medium altitude types - usually Spitfire FR.XIVe, with one flight of high altitude type - usually Spitfire PR.XIX, combining the capabilities and roles that had been encompassed in a Recce Wing, within a Recce Squadron.