Short vacation advice?

Me and my SO want to go on a 4 day vacation by a lake but we’re not sure how to go about it. We’re also not trying to spend a lot of money.

Would renting and sleeping in an RV be preferable to Airbnb or something? Cost or comfort wise? Because then we wouldn’t have to rent a car... We don’t want to sleep in actual tents or a cabin.

We’ve never went on a vacation before so any advice at all would be great!