Been there with a dildo, interesting but cramped. I suspect it is a much different feeling for the lady. For me it greatly limited the physical stimulation but was a hell of a visual one. I'm not going to out the companion, she can chime in if she wants to share. As for doing it with other guys your gonna need to find some dudes with length. Some of us short strokers won't make it into the party with all the obstacles. Plus you are gonna have issues with the possibility of crossed swords. Might make some guys shrivel up in a hurry at the wrong time.
If your playing down this alley looking to be really filled up, have you tried out fisting? Got there kinda accidentally once and the lady went wild, in a good way.
You gotta remember, I'm a little "
ed".