I have some Atera Giro AF+ racks.
They’re the type that clamp the downtube.
Basically they fit anything with twenty seconds of effort.
To load up you put the bike on the rack and clamp the down tube. Then you slide the wheel chocks along the rack to meet the tyres, do up a wing nut to clamp the chocks in place and then ratchet straps through the wheels.
I can get four bikes loaded in about ten minutes (including turning handlebars on kids bikes due to bar/wheel clash).
I did find that I had to adjust the position of the wheel tray relative to the frame/roof bar clamps when I first set them up for my 29r and wife’s long front centre hardtail but my road bike and 26r fit in the new position. One time only job.
Mine came from http://www.roofbox.co.uk who do great package deals…
If you go on their website you’ll find great videos on set up and using nearly everything they sell and service has been too notch when I’ve ordered from them.