Dumas 28” Swamp Buggy ELECTRIC conversion

I built this airboat when I was about 10 years old and just converted it to electric. It was originally powered by an OS .21 nitro engine.
Current specs:
E-Flite Power 25 1250 kv motor
HobbyWing Max10 SCT ESC (120 amp 4s capable)
APC 9x6 electric prop
3s 5000 mah battery (good for about 15 minutes of runtime)
25kg waterproof mg servo
I wasn’t sure if 3s power would be enough, so I spec’d everything to handle 4s. It gets airborne on 3s at full throttle, so I think 4s would be a little too much. 4s would require some stabilizing fins and a water rudder.
3s is definitely more powerful than the stock OS .21 nitro engine. Probably comparable to a .25 or .30. I’m sure 4s would be about a .40 or .45 equivalent.