Originally Posted by panicman
Better idea is to tell him know problem you would love to go and 1 week out cancel on him.
Agree with tteton, this would be a really mean-spirited passive aggressive move I wouldn't wish on anyone.
One thing to remember is that all of us posting here have our stories of this kind of thing happening. And it's always so easy to come up with the worst-case situations when we recall our memories of shitty river trip experiences with trips like you describe. We immediately recall some overweight family with pouty, pasty-faced teenage kids whining about no cell reception, showing up with suitcases of street clothes and makeup and who couldn't handle a night of car camping, much less a week on the river, without serious babysitting.
There's also a chance that your friend has a couple of other rafters lined up, more gear, and his family are experienced campers, adventurous, and ready to jump in and make the whole thing work well. I've had a blast with plenty of river newbies who were great to have along and psyched to be there with minimal direction.
Don't let our worst case scenarios sour you on your friend who you say is a good guy, and the trip.
There are lots of questions to be asked about what type of folks they are, camping experience, other support, etc. before bailing out on the trip. And if what you find out is a dealbreaker, you can always point out what your friend needs to make the trip work, and then condition your acceptance on things that will make the trip work out, and what you need him to have lined up before you commit.
Something like, "Your family sound like great folks but two oar rigs for 11 people isn't going to work. I'd love to come along but only if we can get 2 more oar rigs and a paddle boat to carry 5 people and a couple of the drybags. My buddy Bob can bring another oar rig and I'll make some calls to find a couple more oarsmen to make this thing work out. Renting a paddle boat will only add $300 to the total trip cost, Bob's girlfriend Julie guided a couple of summers and would love to run it."
Good luck with your decision,