Parking was horrendous in the town of Rehoboth Beach! Every single spot is metered parking, but the meters did accept credit cards ($2 per hour - with a max of $20 that would give you till midnight) and they also had an app that you could download to add time to the meter, if you knew your meter number.
But, on the positive, the beach was free to get on and a cop came over to us only once to tell us to hide the obvious alcohol containers and use something more discreet and he would look the other way.
We were there a few years ago and stayed at the Econo Lodge on the main drag. We found for a small fee I think $2 a bus would pick us up at the hotel and take us to a parking lot where a free transfer to a shuttle that ran non-stop back and forth to the beach was. Parking was very bad near the beach and I would not plan on doing that.