Hi Everyone. We are going to be purchasing our first, new to us, used pop up this weekend. I am beyond psyched and have been reviewing this portal like crazy and gathering ideas on remodeling from pinterest. My question is this. Not sure what size mattress comes on either side, but I get easily sceeved out by sleeping on someone else's bed. I have been online looking at mattress costs but am finding the costs WAY more than I want to spend. I thought about a plastic cover over the old one and then adding in a mattress pad to give it a little umph. Thoughts? Has anyone tried a blow up mattress? Please help! Thanks so much.