Why not spread the festivities out over the whole mo? Ask that just a few people come at a time and give them a time window in which to come visit. That way you can put some of them up at your house and they won't all have to pay for hotels.
Keep in mind that people like to feel needed. You can take a moment in a day when you have some close member of the family or a really good friend over to take them aside and ask them to go out and get some necessary dinner item or help you w/ chopping salad. We all love to chat and help in the kitchen. It's enriching to the relationship.
Some people think it's tacky to ask a guest to bring a salad or wine or some other menu item, but if your guests/family/friends are casual like mine, no one will batt an eye at it.
And if a few are staying at your house at a time thru the whole mo. be sure to have them strip the bed when they're done w/ it, and bring the sheets to the laundry room, or have them bring sleeping bags.
AND you and yours' won't be at the mercy of the weather this way.
If this is all a bit much for you, you may want to check out the cabins at your local KOA and have everyone pitch in a bit to get a nice big one. They have cabins w/ kitchens and baths now.