Do I need a trim tab system on my twin tail? I plan on building a single engine H-tail aircraft with retractable landing gear, removable wings for transportation, and either split flaps or plain. My only problem is, do I need a trim tab system to handle the workload, or should the air from the prop not interfere with the lift and cause problems with aileron, elevator, and rudder control, increasing the muscle the pilot must use to handle the aircraft?
Yes a trim system would be a most excellent idea. If you can trim the aircraft such that it just flies straight on when you release your hands and feet off of the flying controls, the flight will be more enjoyable than when you need to keep pulling one way for the duration of the flight, like walking while holding up a briefcase in front of you.

Trim adjusts the neutral point of the flying controls: the point where the stick returns to when released.