Welcome jayman.
"Multiple hands free orgasms" is a pretty lofty goal! I'm sure that is a pretty rare achievement - even single hands free orgasms are elusive to the majority of men.
However, you're on the right track in your idea of "rewiring" the prostate. Your prostate, along with your pelvic floor muscles are key drivers for rigid boners and throbbing orgasms. Most sex advise articles for men mention the benefit of keegle exercises and prostate health.
A good place to start (from my experience) is with an Aneros prostate toy. There are several models, so picking the right one can be tricky. I think mine is the MGX. Many men tout that after some experience and training, they can induce hands free orgasms. I've not experienced that, but it definitely has done a great job of conditioning my prostate, sphincter, and pelvic muscles. I also like the way my nJoy butt plug rides against my prostate.
I've recently been lucky enough to experience multiple orgasms - usually occurs when my wife uses a dildo on me while blowing/massaging my cock. They happen with no ejaculation (but lots of leaking) - just wave after wave of intense pleasure. Once I'm in that zone, the slightest touch has me squirming and thrashing around like I'm possessed. I USUALLY won't ejaculate until after the dildo is removed and I take matters into my own hands OR fuck my wife like a beast. Sometimes I don't even concern myself with ejaculating after so much intense pleasure.
As far as anal vibrators, even though you may not touch your cock I'm not sure I would classify that as "hands free". The most intense anal pleasure I've gotten from a vibrator is using a Magic Wand with the Gee Whiz attachment from Vixen Creations.
https://www.amazon.com/Vixen-Creations-Gee-Whizzard-Marble/dp/B001JI3ETG/ref=sr_1_1_s_it?s=hpc&ie=UTF8&qid=1514733229&sr=1-1&keywords=gee%2Bwhizzard&th=1
https://www.amazon.com/Aneros-HE101-MGX-Prostate-Stimulator/dp/B001AQTVIK/ref=pd_sim_121_3?_encoding=UTF8&refRID=JMCZ6EJKT76N9DQXRZCS&th=1
https://www.amazon.com/Njoy-Pure-Large-Sliquid-Sassy/dp/B00AWR93WM/ref=pd_sim_121_7?_encoding=UTF8&psc=1&refRID=WG6AF1VVDWJ2YXVWGQXX