For me the important thing to reach prostate orgasm is zero penile stimulation, relaxing a lot in a comfortable position, and rotating the toy, not going back-and forth to stimulate the prostate and nothing else.

It's generally easier in something like a bathtub where I can rest my legs high and not have to hold them myself.

Haven't achieved that but anal just felt so nice that it helped with the rest. I don't even feel my prostate that cleanly

I had similar issues and still haven't been able to go hands free. It's been awhile since I've done anything but I'm hoping to start trying again soon.

I have considered a thrusting machine but space has been the biggest concern for purchasing.

I've tried but never achieved prostate orgasm. Reading those that have, I think they'd recommend you focus more on making you and your mood more susceptible to orgasm and less on increasing anal stimulation. Maybe it'd help to pace yourself somehow if your muscles are cramping in the time required to reach O. Explore your expectations first time versus since. Perhaps you were more open and curious that first time, which facilitated orgasm. Now, maybe you're chasing it more narrow-mindedely and are somehow sabotaging your chances of O. I hope you Njoy your wand again ;)