I had an idea that you could replicate the Form II technique Makashi by creating a mod that would place an invisible and inactive melee/lightsaber in one of the Player's Hands and then placing a lightsaber in the other hand...This would simulate the effect of using one hand fighting although not perfect its probably the closest thing we will get to any actual visible differences between the forms. I got the idea from when you equip two ligtsabers one in each hand, pause the game and un-equip one of the lightsabers while the game is still paused the character looks as though he/she is using a one wielding hand technique.

 

so if anyone fancies the challenge

Those are already around, although I'm not sure where you can find them now that PCGAMEMODS.com is gone.

Damn it to the bowls of bloody Hell...I hate it when you come up with an idea that's all ready been done