Earliest R-2800 powered, non-turbo US Army fighter?

How early could a non-naval, non-turbo, R-2800 fighter have been built and deployed?
Who would have built it?

If Wikipedia is correct, the first B-26 combat mission was on 5 April 1942.
B-26's participated in the Battle of Midway.

If Wikipedia is correct, the first P-47 combat mission was on 10 March 1943.
Almost a year after the B-26.

I'm not sure when the 1st F4U combat mission was, but its development was protracted.

Could not a simpler, lighter, non-turbo R-2800 fighter have been fielded much earlier?
At least as early as the B-26, if not a bit earlier?

How many WWII era American fighter aircraft were simple, lightweight and inexpensive to mass produce? P-36 is the only one which comes to mind. So you would be swimming against the tide of American fighter aircraft design standards.

We have discussed it some time ago:
http://www.ww2aircraft.net/forum/av...le-stage-r-2800-missed-opportunity-33885.html

The Corsair's RFP was issued in February 1938 and the aircraft's first flight was in May 1940 (Significant Dates in Corsair History). If the USAAF issued the same sort of spec, there is no reason that the schedule to first flight would be much different. The posited USAAF R-2800 aircraft would not need the added step of carrier qualifications, so production aircraft could have been delivered a few months earlier, maybe with production deliveries starting in June, vs September, of 1942.