Polite way to limit guest list

StephanieEris

I'm sure this is a common problem, but I haven't seen it mentioned here recently. My FI and I originally wanted a small wedding with 30-40 guests, but it's grown way too big for numerous reasons.

One of the reasons is that whenever we put a new guest on the list, we automatically add his or her "+1".

Our proposed solution is this: We would invite a guest's serious BF/GF, and we would also allow a guest who doesn't know any other guests to bring a "+1". But for our single friends who will know a lot of other people at the wedding, we would only put their names on the invitation- they would not get a "+1".

So my question is this: do we have to allow every single guest to bring a "+1"? Is this solution is horribly offensive? How did everyone else limit their lists? 

I'm just trying to be very concious of etiquette and to keep the guests happy and comfortable, all while watching the budget. Thank you!