QAUTOTUNE on a string

I’m trying to tune a Flitetest Super Bee as a twin tailsitter. My challenge is that it can’t actually sit on its tail. I’ve seen people successfully tune quadplanes by suspending them from a string. I tried that, but when the plane climbs enough for slack to develop in the line, the line wraps itself around one of the propellers.

The plane is stable in forward flight, so I suppose it’s possible to enter QAUTOTUNE from FBWA. I’m chicken to do that though. QAUTOTUNE seems too violent for me to try it without the safety of either suspension or the floor.