Personally, I'd plan on budgeting for more equipment ASAP Doing that much swapping each night, something is bound to go wrong sooner or later. Also, with one chassis, one ESC, if something breaks, you're out of all classes. But, I understand...it takes time and money to get going initially.

You don't "have" to run blue, yellow and orange wires. In many of my cars/trucks, I've ran all black wire just for aesthetic reasons. But, those wires were installed while at my work bench with no time pressures and are hard soldered. Between races and with having to take out one motor, install a new one, set mesh properly and then connect the wires, things could get pretty hectic. Usually, when I am rushing something (especially something electrical), things often turn out bad in a very bad way.

If you do this, I'd at least suggest that you do something so that it becomes fool proof when plugging in wires...colored wires, different connector types, wire lengths, etc. Also, check your solder joints often. Tugging on wires repeatedly will begin to weaken solder joints.