I've solved some of my health challenges and got back into something resembling shape. Now I'd really like to get back out to a martial arts club.

Just one problem:

I've got decades of experience, zero interest in learning some n-random school's beginner set before they let me get in a ring and do some san da and no contacts in Toronto - my school is in London, ON.

So how does an old hand get back out into the local community after an extended absence? Should I bite the bullet and go to an open mat MMA gym? Or is hanging my own shingle my only approach? Or are there schools that have some method of assessing the general skill level of veteran walk-ins?