Hotel booking

Sorry didn't know where else to post this! So I'm 19, and my husband is 20, and we are expecting our 1st. We are due Sept. 25th, and my husband is in the military. He gets deployed in Novemeber. Anyway, before the babe comes and before we leaves for a 10 month deployment, we really want to have a 5 day vacation at the beach. The problem is, is that most places you have to be 21-25 to book a hotel room. We both have credit cards, are very responsible people, we just don't understand why we can't book a hotel room at 20? We aren't going to be loud, we are going there for a "baby moon".  Does anyone have any suggestions of what to do? I haven't been to the beach in 2 years, and would love to go before the baby comes And really don't want to have my parents come with us (you'd have to have someone over 21-25 in the room with you). I just want is to be us