Boardwalk Inn.
Only during the busiest times of the year will the gate guard issue a time limited parking pass. Christmas, Food and Wine Festival, Fourth of July, etc.
The parking across the road is not always available to guests. Stop at the gate before going to the alternate parking lot.
Simply tell the guard that you are going to have dinner on the boardwalk and you should experience no problems.
You can also park at the Swan. Walk in to the boardwalk, have dinner and then enjoy the show at EPCOT.