When do you make that extra effort and when do you go with not wanting to, being tired?

My DH and I are going camping this weekend with son, daughter-in-law and grandkids. This will be the third year we've done this; the other two years were in late September but it was decided that this year we should do it when the pool is open. We go to a great campground and DH and I stay in our RV next too/across from/near the cabin we rent for their family.

My problem is we were going to do it for two nights this year, Friday and Saturday, instead of just one. However, Thursday, DH and I have our quarterly doctor's appointment in the morning.

I will need to get my prescriptions filled at one store.
I have to plan what we all will eat and go to another store (the first doesn't have good meat) to get what I plan
We have to pick up, stock, and clean the RV
One of our cars is at the mechanics getting fixed and has to be picked up
Laundry before and planning for cat care during
We need a grocery shop today; we're out of other things

I don't do pool and the place we go to doesn't have many trees/anything for "adults" to do; I'll be sitting all day in the camper (has lots of active kids stuff to do; one or both of the son/daughter-in-law go with the kids to each of their activities). We have AC but I'm not thrilled about spending my Saturday cooped up in a tin can?

I told my husband this morning I didn't want to do both nights but then got an email from daughter-in-law (who is out of town and is flying in Thursday with the kids from Florida - so, they'll only have one night in their own beds and she will be doing turn-around preparing of her own) saying it was "perfect" that we were going both nights.

I like to get up early in the morning so I can have coffee made and juice boxes for the kids (late September it's hot chocolate :-) and breakfasty sort of pastries, etc. They get up very early and usually son gets up and gets them out of the cabin so daughter-in-law can sleep in. The idea of doing that two mornings in a row, getting up at 6:00 when I normally get up around 8:30. . . Neither my husband nor I sleep very well in the RV for a night or two; the bed is a bit too small for us, not what we're use to.

Do I bite the bullet and act gung ho for two nights, exhausting/boring myself or do I request only one and feel guilty I might be spoiling other people's fun?