Good plan Show.
I did my first race season w/only 1 truggy.
This season I'm going in with 2. I only own one motor, and one personal transponder. I have enough receivers to prep both radio boxes. (except that whole transponder thing) and while I have enough servos to set up both radio trays; they're not really similar, so I'm leaving those off as well.
The rollers will both be as identical as I can make them. This will mean some extra upkeep on the practice roller as I'll be trying to keep it somewhat "fresh" like the race roller.
When I transition from practice to race rollers; I'll move the motor, and the radio tray. I'll have my spare radio tray setup w/servos and receiver, just in case; but it'll mean adjusting endpoints & whatnot, so I hope not to have to bounce between radio trays. [This way also protects me from accidentally leaving the wrong model selected on the Tx.]
Not sure what I'm in for just yet, but we'll see how the season goes.