yes, outside storage takes it's toll over time, but these things are high maintenance anyhow, so just need to keep up on it.
Makes good sense to get a bunkhouse if the grandkids will be regular. If not, maybe shop for what YOU want and they will be fine sleeping anywhere. They will be happy just being there.
David & Lynn
2014 Coachmen Chaparral Signature 327 RLKS
2016 Ford F350 Lariat CC Dually