Wife’s request.

My wife and I exchange ideas regarding our SPH fetish. I asked her if she would be interested in pegging and she was not pro or con to the idea. She had asked me to look into strap-on’s which I am doing. She asked me tonight if I would allow myself to be as she put it locked up when she wants to induluge her fantasy. I have a question are these type of devices uncomfotable to wear for a short period of time? And how do you figure out what size to order? Sex toys do not offer refunds if you order wrong any suggestions would be appreciated.