RE: IC engine altitude record ?
I think one would have trouble finding a location that has a airspace that is relatively protected from full size aircraft flying by. But maybe where the rocket people fly their rockets is a suitable place. Maynard got lucky with using a military base with a restricted airspace at the time he was doing it.
Here in the USA the unwritten rule is that the RC airplane has to be within visual sight at all times. Plus we aren't really supposed to fly higher than 400 feet in many locations within so many miles of a airport. If they ever get the new FAA rules done they'll likely have new rules for FPV planes. Our other problem is the FCC limited the RF output of our modern RC systems so that range is more limited. RF amplifiers to boos tthe signal are pretty much all illegal here. To get around that, one would likely have to use the reserved Amateur Radio 51mhz channels for RC and boost the power on the TX from there. Maynard may have been using the 51 mhz radio channels for his altitude record too. Of course with less RF power, I suppose one could use a parabolic dish antenna and point it at the airplane for the whole flight too. Very tricky, but possible. Anyway, that had me thinking that one would likely have to go to a different country with different rules in order to be able to try to beat the altitude record as here in the USA if will be hard to do it nowadays. I don't think anyone has beaten Maynard's 26,000 feet plus altitude record yet either using a IC engne, and it was done way back around 1963 if I remember right.
But I am sure the military have drones that have beaten his old RC record, but would they count?