Rules for wedding gifts??

My finance and I are going to have a private marriage ceremony and, then at a later date, we will pay for guests to have nice dinner in private restaurant/hotel banquet rooms in each of our respective hometowns. We are doing this because of lack of money, where this will be cheaper than a formal ceremony/reception. Plus many in our families can't travel due to health, money, or jobs. If we register, how to we let people know?? What about the invitations?? They won't say "wedding" on them, just dinner reception. We are really confused....