Think of how much more fun model trains are since we have left the fixed location transformer. The remotes (and everything related to walk-around control) have added a great deal to the hobby starting with HO in the 1990's, to now. We need to give the kids that same feeling, I think.
I might install controller holders then attach a flexible wire (fishing leader wire) to each controller at a length to stop it just short of hitting the floor if dropped. In a 36" layout height, the "wander" room might be up to 6 feet right or left. This would leave it available to hold in small hands and walk (a little) back and forth to see the train.
Also a 2-conductor wire from a 4.5v voltage-controlled source to each remote would successfully eliminate the AAA batteries and turn off when the layout is turned off.
If you need the ability to have different locomotives to rotate or for maintenance, the kids could use permanent remotes as above. But buy 2 or 3 of the same LC+ engine that will run using the same "captive" LC+ remote.
Oh yeah- and this system still leaves the layout open for any other digital control system locomotive run by adults.
