Nice job . Might be an idea to replace some of the more crocked ones with something a little straighter , there are gaps a shell or magnetic grenade could get through
Notice these logs are also longer so they can wire / tie onto the front & rear lift rings .
I have a set of extra tracks like those on your kit , plus a full sprue of the Easy 8 style wider tracks ( E sprue )
You don't really need a lower hull , make a box out of sheet plastic , add track parts , a extra trannie nose from the parts box , and mock up a rear plate depending on the version your M4 engine deck is , and your good to go . Even if you just leave the rear pate blank , in a game it's usually facing you not your opponent .