First post and I have a few questions

I bought an impulse 31 as a project (I think I like building them more than running them) I added the speedmaster trim tabs and the dual rudder kit. I upgraded to the leopard 180a ESC and the leopard 4074 1650kv motor with the OSE HD flex shaft. I'm running separate cooling lines for the ESC and the motor. I plan to run 6s power
My first question do I need to support the back of the motor? It's longer and heavier. Second I want to prop up. The Prather 215 is similar to the stock prop and the 230 is a monster but the motor seems to have some pretty heafty torque. What do you guys recommend?