We bought a back-up inflatable mattress that we travel with (we have a car). But it was a cheapy and is so uncomfortable and narrow, we only used it for one sit of 5 days as a back-up. On the other hand, we borrowed a fancy double bed self-inflatable mega bed from our in-laws and it was very comfortable! You get what you pay for. Unfortunately, you won’t have any ideas if the HO is stingy or not 
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