I’ll be purchasing a hitch mounted bike rack for our car this year, since my daughter’s bke is getting too big now to fit is on top of our 2-bke-rack. Ideally this should not only be useable for family holidays but also for trips with my unicycle group. With other words, it should also fit 4 or more munis. Du you have any advice on what to look for? I don’t want to know a specific model but more what features a rack should have to safely transport munis.
I would look at the kind that clamp on the tires, like a Kuat piston or an Inno INH142. I have a 2-bike Kuat Piston, and I have been able to put 2 non-36”unicycles on one bike track. You can commit a unicycle to each track and use the one clamp to hold down the seat and seatpost, or you can put two unis in a track together with one wheel clamped by each clamp, and then lash the seatposts together. It is very space efficient.
You should check the rigidity of the rack, it should not be able to move at all once locked.
Also check if you can lock the unis (by the wheel locks, and by the frame pinches) and the rack itself.
Another good thing is the possibility to lean the rack to open the trunk without removing all the bikes and the rack itself from the car.
Thule does some really good racks (it is what I use) for example.
Not sure about availability in Germany, but MaxxRaxx has served me well for many years