Rear mounted bike racks can be done however they are problematic due to the excess bouncing that occurs (school bus effect)and the simple fact you can't see the bikes while traveling.
For those reasons I prefer an Arvika pin box bike rack. There is no bounce at the front end of the RV and bikes are always in view.
Arvika racks are made for 5'er and TT's.
I have been using an Arvika rack for about 7 years. I used the rack on my TT for a few years and the adapted it to my 5'er.
Arvika bike rack images
19'Duramax w/hips, 2022 Alliance Paradigm 390MP >BD3,r,22" Blackstone
r,RV760 w/BC20,Glow Steps, Enduraplas25,Pedego
BakFlip,RVLock,Prog.50A surge ,Hughes autoformer
Porta Bote 8.0 Nissan, Sailun S637