Nothing was preventing people from making streamlined tactical and/or dive bombers.
We can again take a look at Battle's portly appearance - it's deep and long fuselage and it's big wing. Wing area was 90% of what the Blenheim, Mosquito or DB-7 had - not good when the Blenheim has 2/3rds more HP ( even after the engine-related drag does it's number on it)
The Hind and Battle could have a man lying prone using a bomb sight though a hole/window in floor for better "accuracy". Again we are back to what do you want the plane to do.
You could cut down the Battles bulk by using only two men and eliminating the bomb aiming function (with required a steady speed and course (and altitude) for a number of seconds before bomb release. For the British (and some others early on) you have the airfield problem. For the British, they wanted to use the 3 man crew, carry four 250lb bombs, enough fuel for 1000 miles AND they wanted to get the plane out of the standard 500yd field. In 1936-38 that meant a big wing. In 1938 they
started making some of the airfields bigger. They
started fitting better props (better acceleration during the take-off run) and they had figured out how flaps worked so the plane could actually land back the same airfield.
I'm probably a wrong person to accept a Japanese aircraft to be powered with the Japanese copy of the DB 601
For them - a radial in the nose, 'ordinary' wing with a retractable U/C and there it is.
Well, you keep asking for fast
The Kawasaki V-12 gave them 850hp for take-off in 1937-40 (30 less than the Merlin) and 950 hp at 12,470ft.
The Ki-32 was faster at 13,000ft than the Battle
Problem for the Japanese was in 1937-1940 they needed really big radials to get big power. Hundreds of the early Ki-21 bombers used the same engine as the Ki-30
Not a lot to choose between the Ki-30 and the Ki-32. In 1940/41 the Radials with two speed superchargers (and other improvements) show up
And perhaps you could have your fast bomber then. The Japanese were not backwards. They had done experiments and calculations and retracting landing gear aircraft often did not show much advantage in the under 300mph speed range as long as due care was taken designing the landing gear. over 300mph it became a different story.
Here the 'bomb chambers' like on the XF4U-1 might come in handy to help out with the 15 kg bombs; the 50 kg bombs should probably fit in the 'main' bomb bay under the fuselage. Once these are proved bad, and engine power is up (needs more fuel), have on that place fuel tanks instead.
Just pointing out that Army requirements and Navy requirements are not the same.
For the US the requirements for the A-20 changed.
In the A-20, A-20A, and A-20B there were racks for eighty (80) 30lb fragmentation bombs in in vertical chutes/tubes.
Max load of sixteen 100lb bombs was provided for and since the US Army and the US navy didn't use the same bombs at this time the Army also wanted to hold four 300lb bombs, two 600lb bombs or one 1100lb bomb.
The British didn't want the small bomb storage but did want to carry 500lb bombs (only two ) but since their bomb was longer than the American bombs the bomb bay was lengthen by about a foot. The US got rid of the requirement for the little bombs while they were still sorting things out but the space in the upper bomb bay was used for first a 100 gallon fuel tank and later up to 325 US gallons could be put in the bomb bay with four US 500lb bombs below.
depending on year and country the intended bomb load could make quite a difference to an air plane even if the nominal weight was the same (A-20 bomb bay was 62.5 in in height as the 30lb bombs were required to fall free of the tube before the slipstream hit them.
And the eighty 30lb bombs were the max bombload of 2400lbs.