@Susan1188 This topic has brought a lot of interest of for and against. My answer to your question is yes I do provide an extra mattress because when I looked at the Pack and Play/travel cot there was no mattress and the wrap around cover that goes in the base was a thin plastic would be hard for a little one. I thought I wouldn't like to put my child on it. So looked online and found one which folds up and one side has a plastic cover on oneside for waterproofing for accidents.
When we first listed our cottage was suitable for families and had no travel cot on the listing but was asked twice by families if I had one answered with a no. I then thought about it, priced them, then looked at getting a 2nd hand one. But eventually got one of facebook for free, my thoughts if not good enough I could just put it in the rubbish. But, I was lucky I got one in good condition and gave it a terminal clean as I was a nurse and had worked in childrens ward and everything gets cleaned top to bottom.
The travel cot does add to your cleaning time. When families book with infants I ask them do they want to uses it and then we asemble it for them making sure that it is secure in case of accidents.
Your second question was about supplying sheets, yes I do . I made 2 sets to fit and supply a small pillow with covering. But, I do tell them to bring their special blanket and have (2 in case they happen to forget). not had to use so far.
What the travel cot highlighted to me was what if a child sleeping in the single beds has an accident and would the mattress protector (not fully waterproof) if they wet the bed.
So now I put a dispossable padded waterproof sheet on the travel cot under the sheet and leave a couple of spares. I also put a couple on the single beds and mention to the parents that children get tired while being at the beach and they sometimes get disorientated in different bedroom and could have accidents.
All the parents have been very considerate and have put them on the bed, left the unused ones intact and not taken them home. To me this is less costive than having to treat the mattress.
I hope these answers help you with your research on the topic of supply a mattress and sheets. Also you could say to the person when booking that the travel cot has the basic mattress supplied by the manufactures and you may need to supply your own mattress along with the sheets and bedding.
I feel that Airbnb want us to upgrade every aspect of accommodation but the more we take on, the time and money, cleaning is added onto the hosts. it was also mentioned that you could refer them to an equipment hire place and it becomes their responsibility.