Nothing. The FAA in the US is pretty good about these things and as long as you stay below 490,000 ft AGL and are flying a sounding rocket (eg not trying to make orbit). With that said, well-resourced doesn't matter too much, it's more knowledge and experience. CSXT attempts were done by a team of aerospace engineers experienced in these types of things in their day jobs. They reached space (above 100km AGL) twice. USCRPL has been doing this for well over a decade, and have also reached space twice. And they've had heaps of failures along the way.

TLDR; Going Mach 5 in fairly thick atmosphere is exceptionally hard to do without encountering a rapid unscheduled disassembly. Flying a two stage to space is more efficient and less rough on the rocket, but no one has done that yet as it's quite a bit harder that a relatively dumb 4fnc rocket.