We are having a small semi-destination wedding and would like to extend a plus one to all single guests out of courtesy. However, we know a lot of single people (mostly extended family members) who probably won't bring a plus one, and if that is the case we would like to invite a few more additional people. (I hope this is not considered B-listing, as it is not our intention -- all invites would still go out at the same time).
My question is, is it ok to ask these singletons before we send the invitations if they would like a plus one, and who that person would be (so we could include their name on the invite)? Would it put rude pressure on them to name someone? What if they change their mind later and we no longer have space, would it be a faux pas to say no?