Here’s something that will help the adventurous sims in your families. If you’ve got both World Adventures and Generations installed, buy a sleeping bag for each of your adventuring sims and then put the sleeping bags in your sims’ inventories before you send them off to any of the adventure worlds.
If your sim is new to adventuring, you will have to do this before he leaves for his vacations because you cannot enter buy mode on the community base camp lots. You won’t be able to buy a lot in any adventure world until you reach visa level 3, and by that time you will have gone through most of the tombs already.
When your sims have a sleeping bag on their adventures, they can find a place to sleep in almost any tomb because the sleeping bag takes up only a couple squares of space whereas the small tent needs much more space (and the luxury tent that the special merchant sells requires an extra-high roof above it to accommodate the spire at the top of the tent).
Just be sure to have your sim put his sleeping bag back into his inventory before leaving the lot.