We usually stay off site. Okay, first, if you RD, you get GREAT parking! You're within the first parking lot and can easily walk to the park... no trams, which means when you're tired and ready to go home, just walk to your car.... no waiting for trams.
There will always be lines in WDW, but the size of the lines increases as the day goes on. RD, get in a few high demand rides in the first hour and then do the mid-range rides, have lunch, do your afternoon fastpasses, while slowing down your pace, because, after all, you were up for RD and lines and crowds are worse in the afternoon. Do some shopping or tasting treats/drinks or find a long dark ride to relax in...
We usually go home for dinner and my DH is done by then, but once during a trip we'll stay and have dinner somewhere in the World and take our time going home... to our own private pool and/or hot tub. But if you're staying for fireworks, take it easy later in the day, either an afternoon break of some type or a relaxing dinner or a dessert party.
But seriously, people like to sleep in on their vacation, so there are the fewest people in WDW in the early mornings.
Also, since you're off-site, avoid any park that has EMH in the morning, as your benefits of RD will be gone. The trick is to get there when the lines are forming, not after they've been formed for an hour.
If DH still need convincing, check out the ride wait time estimates and compare the morning hours to later in the day.