A 5th wheel, or a 35 foot long trailer, we both share the same problem.
When we sight see an area, we try to find somewhere we can park the 57 foot long train and then walk. So wherever we want to visit, has to be within walking distance of where we park.
We've not had any issues parking. We've always been able to find somewhere. The biggest obstetrical we have to over come is our pets. Cold and winter months is no problem. They stay in the camper while we do our thing. But in the Summer, when it's hot, and were sitting in an asphalt parking lot somewhere, and the inside of the camper and truck is over 100 degrees, the pet's become a real concern. So, the bottom line is, we simply do not visit or go anywhere the dog cannot go. If we do go (say... into a grocery store or something), one of us stays outside with the dog while the other does the shopping.
Sight seeing is almost always outside. We do not enjoy inside man-made, cinema dramatic, artificial, or electronically controlled stimulation. Even when selecting restaurants to eat, we hunt down places with outside seating, so the dog can come along.
Parking? not a problem. Get out and walk. If you have to, see the attraction, then move the camper to a new parking lot. See the attraction there so you don't have walk so far.
If the site offers tours, like buses, coaches, trains, or what-not, then take advantage of those options.
Good luck.