Congratulations Krystenmae!! Yes, we know what you mean. We are wedding planners in Cancun (Our resort is The Royal Resorts) for Civil wedding services we suggest to the couple get it done at their home as it is less expensive and easier for them.
"can't we just go to dinner after and use the "nightlife" as a reception?"
It depends what you want but It's not a bad idea and It's very normal in our destinations.
Do people do this? Yes, the people do this. <3
The reception is a good chance for share special moments with your guests (family and friends).
If you think about to give it an opportunity and your venue in Mexico has beach, we suggest you do it on the beach is really beautiful and unforgettable. Also, your guests will be less than 20 persons, this will be really intimate.
Remember, It's your wedding, do what you love, invite the people you want, dance to the songs that bring you most enjoy... Be the king and queen of the rest of your life and enjoy all moments!!
~Sarah~