I took the liberty of modifying your suggestions for mounting the motor controlle
Its a prototype and I’m looking at ways to micro size it. if I cannot, I’ll replace all the hardware you see; below, with stainless steel.
I dug up a brass hinge and bought a angle iron for mounting, angle aluminum for horizontal support, stainless spring and a turn buckle for tensioning.
I removed the dome wheel at the motor mount post, because it pulled out of the dome track, (but May re-install it.)
This setup allows the whole motor assembly to disengage the dome track completely, should one would like to move the dome by hand.
Theres a sweet spot, at the turnbuckle, so you would need to find that as to not tension it too loose or too tight. The latter would pull the wheel out of the track. Too loose and the gear could skip a tooth, here and there.
The aluminum angle support is connected to the wall lip (needs a Teflon bushing there,) and secured at the motor support where the original bolt secured the wheel. Again, the wheel removed for now and it’s bolt/axel is not in use.
Thanks for all your ingenious ideas and hope this helps, further down the road.
PS: I’ll layout all the hardware after I put together my new home.