dire's post in Science Jr. keeps exploding on rentry was marked as the answer
Using a big, flat radiator acts like the Space Shuttle's heating tiles. Just be aware it also adds a ton of drag.
You can also pop it into a mk2 cargo bay for safe keeping, and that can give you the flexibility to deploy small satellites when you aren't doing science. If you have airbrakes on your SSTO you should be able to slow down enough, but they do tend to get pretty hot during reentry.