It's not possible, around here anyway, to get a tub to 90 degrees in the winter with heat tape. It's just not possible. An inch above the tape and the air will be room temp. Heat tape, rope, UTH's, etc don't heat the air.
The reaon I asked this was because it was mentioned aquariums may not be the best enclosure to keep snakes in.
However, as the discussion progressed I realized I was thinking from a tub perspective and my thoughts relate back to this thread:
http://www.monsterfishkeepers.com/forums/showthread.php?t=283571
So when it was mentioned there are better alternatives to glass and the oven comment was made, I had trouble understanding how throwing a heat lamp/emitter on a glass alternate was any different than than just using a fish tank.
You are offering the use of heat tape/rope as a solution to the oven dilema. I think the oven term stems from the belief that in order to keep temps up in a glass tank, you need to pour down tons of heat, most of which is escaping because glass is such a poor insulator, not thermogradient as you indicated.
Yes, I keep reptiles.