I think a lot of people do a welcome dinner instead of calling it a rehearsal dinner, that way if you have a rehearsal you can just have the key people at that and then meet everyone else for a dinner. We invited a lot of people to our rehearsal even if they weren't directly involved because so many people traveled and we knew it was a chance to get to spend some more time with them.
ETA: I just noticed you are from Napa, that's where I was married, we had about 50 people invited to the RD and we went to a mexican rest. in yountville-the name is escaping me right now and had the entire patio. It was a blast and I think that if you want to have everyone (what's 10 more people) you should go for it!