i made a tank up for golden geckos a couple of years ago, if i can dig out some pics i'll put one up.

Basically it was a horizontal tank that i customised to be used for arboreal creatures. The light i secured with aquarium, sealant... i was worried about the heat of the tube softening this, but never had any issues. Again the stones at the base i used sealant for, but it was awkward, some secured fine, some dropped off, in the end i gave up and stacked them lol.

I don't know about hot glue, but for the light sealant will be fine

look forward to seeing some pics