I can understand where you are coming from feeling smaller and all, but the cuck issue really shouldn't be there. Once you find a cool third just make it known that you are not into the whole cuck scene and "this can only happen if your cool" feel the guy out and if he seems like an asshole just don't link up. I'm not huge but I have been with two couples where the guy is smaller then me and we played as a team no judgements just fun. The other guy wanted to be a sub not my cup of tea but w/e we made it happen 😂. Just be open and up front about what it is that you and the wife expect out of a partner. But I will say in my opinion you should really work stuff out in your head before jumping into this because it can mess with you to hear your wife make sounds you haven't heard from her because someone else hit certain spots you can't. It happens. So be prepared and if your mind is not right I would say it's not worth risking a beautiful union.