Weight Limit 1985 Presidential 26 Holiday Rambler Class C

I would start looking into digital pianos. Beside weighing about 575 pounds less, it would actually stay in tune and keep working properly after bouncing down the highway.

As Farmboy said, there's a sticker on the driver's door that gives the vehicle and axle weight ratings. Then, you can take the RV someplace with scales and get it weighed, and see how close you are. Unused payload is rarely in copious supply on class C motorhomes, but there is quite a bit of variation between barely any and some.