comments:
As a 6'8" guy, can I hijack the top comment with a real answer? Go to a hardware store. Buy a single shower tile. I bought a single white hexagonal one for a few dollars. Buy some ceramic tile caulk. Apply a zig-zag layer of caulk to the wall where you want your tile (wouldn't be good for a whole wall of tiles, but it's fine for holding one tile) and then place the tile and caulk around the edges, smoothing the caulk with your finger. Use some masking tape if you want the caulk edge to look nice. Then you buy one of these suction cup shower head holders and put it on the tile. Stick the tile high up the wall on the left side of the shower and OP will easily get another 6 inches or more of height. And a land lord isn't going to give a shit that you installed a single tile. Worst case scenario, you rip the tile off and patch the wall before you move out.
We use this one. https://www.amazon.com/dp/B07T5SVXBB?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1&th=1 It's not perfect but it gets the job done.