Have you tried that? You can't bend over because there is the wall in your face. You have to spread your legs really wide otherwise you can't get close enough because of the wall. Then there's nothing to grab onto in front.
I was up to that kind of acrobatics when I was 30, but it's getting kinda tiering.
Every bidet of the spraying upwards sort that I have used has a control to move the nozzle forward or back depending on your chosen... "target". In Italy, most home bidets were the type that are separate from the toilet and just have warn/cold taps.