Well... I wouldn't advise against using flaps if you have them.

I do agree, you should do your experimenting at a safe altitude.

Flaps are a huge safety item when making landings with a heavy airplane. (also when taking off) Just a small deflection can tame a tendency to tip-stall. (Flaps over up to 60% of the central span... not flaperons)

The standard deflection for a full scale P-51 is 7 deg flaps for take-off for just that reason. It has been proven that flaps on takeoff can slow the acceleration of the plane and can make it require more runway to lift the wheels... however its the resistance to tip-stall that makes them useful at low defletion angle.

Trying to land a full scale P-51 or Corsair with no flaps is asking for trouble. Either you land "hot" or you tip-stall and wreck it. The high speed landing isn't a great idea... they tend to want to "trip" and plant the prop in the pavement. (can be done... but you better be good to try it.)

The P-47 has some of the same characteristics which would make some flap deflection a good idea for increased tip-stall resistance. Practice slow flight high without flaps... then with small deflection, then with larger deflections... I would just about guarantee the most stable stall characteristics will be with 5 to 12 deg flaps.