Since the "glass lifter" suction cup grab bars are not ADA compliant, adhesive ones would be even less so. Your options is to figure out how to attach an adhesive pad to regular grab bars or modify a towel bar with adhesive pads. If going wall to wall, you can cut down a shower rod that is pressers attached and just replace the foam pad with an adhesive pad. Just know, none of these replaces a real ADA grab bar and nothing says they will even work when needed, but it's the only option.
1994 Itasca SunDancer 21RB - Chevy G-30 chassis.