I've been wondering the same thing. This will be the first winter we have had the gliders. My apartment has oil fired hot water heat with baseboard heaters similar to electric.
My two males don't bother with them at all, but our girl (Sune), loves crawling around inside of them. We try to discourage the behaviour. We use they 'hey look over here at this treat!' technique, which usually works for a moment, but then she wants to go off to explore the heaters again.
A tent sounds
great and it is definitely on the things to purchase list, but I would also like to find a way to block their entrance to the heaters themselves so that they are able to roam freely at times.
I have been tossing around the idea of using long velcro strips. One just above the heater and one just under it to attach screen mesh to. It just seems like a very cumbersome way to do it.