" I've done that alteration for two locos years ago.
The caveat is that there's only one channel stick ( usually the left vertical one ) that stays put in the position you push it to,
the others are all of the return-to-neutral type.
I think I've described already in this forum how to modify that for two-loco operation,
i.e. make the right vertical stick a shift-type, too.
It is easy to bind two receivers to the same transmitter, provided you use separate ESCs with them.
There's channels 1&3 for one (left) loco, and channels 2&4 for the other (right ) loco.
The idea is NOT that you run two locos simultaneously, except when doubleheading maybe,
but to minimize the number of transmitters to use when operating singe-handed.
It is just fun to have two locos run alternatively for some complicated switching and the like."
Is this basically what you have done ?
It looks interesting ... Kinda 'stick-shift' styleee !
No, that's a version where I just wanted to have well-defined neutral and headlight-switch positions.
True, the guiding slots are held in place by double-sided sticky tape.
The material is white plastic sheet.