Kind of like that mate, but i would keep the motor where you have it on the current versions, but place the cells (in the orientation you have them on that screen shot) and place them right in front of the motor and under the top deck/belt.
The cells are a hell of a lot lighter than NiMh granted, but still weigh in at 280grams plus, if you could keep them central i think that would save you having to use ballast to balance the car on the electronics side - it could then be used to tune the car as the driver needed...and forget being allergic to saddles, if it works better the TC boys will soon convert
Thats just my opinion though mate, if you have it working well for you though thats all that counts!
How close are you to settling on a version for use? Are you looking to sell a conversion kit or is this just a project for yourself?