If I wanted to party at night in downtown Nashville, I would probably book a hotel room downtown for the occasion. Knowing what downtown Nashville is like (a daughter lived there for a few years) I tend to treat it the same as I would a visit to NYC's midtown theater and shopping districts, Chicago's Loop and Near North Side, or San Francisco. In congested cities, I like to be able to get around walking or using public transportation.
For me, visiting a city for the night life is something different from my RVing experience. I haven't gotten stuck with the idea that I need to use my RV on every trip I take. I sort of started that way, but it only took a couple trips to places where I had to park well outside the places I wanted to visit, to get over that idea. This adjustment of travel mode is probably easier because I travel often to big cities overseas, where taking my RV would not be one of my options.
The RV parks are along Music Valley Drive, so that visitors have ready access to the Opryland complex, sort of a theme park version of Nashville. While there are shuttle and tour services originating in the Music Valley area, they will not be running to the downtown area at the times you will need them. You'll need a taxi, whether conventional or pirate. Taxis are $25 flat rate between downtown and the airport, you might be able to negotiate that for downtown to Music Valley Drive, which is a somewhat shorter trip, although return fares are less likely.
Even if I expected to be able to drive to and from downtown Nashville in my towed vehicle, I probably would choose not to do it on a weekend. The supply of parking in the entertainment district falls way short of demand on Friday and Saturday nights, even with valet services to make the run to more remote storage locations.
Tom Test
Itasca Spirit 29B