Can a park a motor home for a few hours for a family get-together?

There is charge for that in the boat loading area, to the left as you get in

Yes

I've seen smaller ones parked there. Don't know if there is large enough parking to accomodate a really big one.

I do not think so. the park closes everyday at sunset. I think 6:30-7.

Sure

I'm not sure I've only been there once.

Yes, I think there is a fee.