If you use the slip ring Stanley sells that gives 4x10a motor wires and I think 10 or 12x other wires. That should be plenty for your lower hull functions. I know you're using an 8 channel setup but if you upgraded the board to sbus you could run a tiny drone receiver which saves space.
I can get a 3s pack in mine ok but not sure how space in the turret compares to the tamiya.



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