New enclosure heating advice

[GyGbeetle]

Just bought custom made melamine 5'x18"x18" enclosures for our boas. We're buying 4 total (2 have already been purchased). And I really am at a loss as to what would be the best heating source. I'm thinking UTH probably won't penetrate the floor of the enclosure. Currently, we have a ceramic heat bulb inside (75w), but it gets way too hot, and warped the top of the plastic hides that were directly underneath the bulbs, so I freaked out and turned off the bulbs. We have the heat source back on, hide is on the opposite side of the enclosure, water dish is underneath the hot side, but I'm still freaking out.

Was thinking maybe an RHP? But that will take some time to ship. What about heat tape? Inside/outside the enclosure? Inside the enclosure, what do we do to cover it up?

Please no mean comments. I'm seeking advice and learning here. The snakes are safe and we can always put them back into their original enclosures until we get things figured out with the new ones. Ambient temps in the house are 78 degrees, and ambient temps in the enclosures have been 80 degrees, so not having a heat source 100% of the time for a short duration won't have a major impact on their health. I just don't know what the best thing will be. We've always used UTH on glass enclosures, and they've worked out really great. We just got a boaphile, and attached an RHP; took about a week to figure out if it was providing enough heat or not. Now we have these ceramic heat sources, and I'm not happy that they warped the top of the hides.