Uhhh... That's a bit tricky.
Tie up as short a VT as you feel comfortable with. I think mine is about 30" before I tie any knots in it. I use double fisherman, looks like you do too. Rig your tending pulley, carbiners, all the other stuff, and put it where you think you would like it to be when you climb.
Measure the distance from your bridge/D rings/saddle to the botttom hardware of friction knot assembly. Make a little rope bridge that spans that distance, and you're in business.
I noticed that your VT has too many crossovers. You should have 7 loops total. (four loops on top, crossover1, then crossover on the other side of the rope, then clipped to carabiner & slack tender pulley) Given the length that you were working with, you probably needed the extra wraps to make it hold well. I'll bet you like it much better after you make it a good bit shorter with fewer, tighter wraps. I'd take that existing tress-rope you have, and see how much I could shorten it by moving one knot up the line until it acted right with only 7 loops.
The VT I use on my buckstrap is probably only 6"-8" long when loaded down with my weight, so there is not much slack to take up when I yank on the free end.