How to calculate lot rent from total POH rent?

Looking at purchasing a park that has 100% POHs. Current owner does not separate lot rent from home rent, but merely charges a flat fee for rental. All utilities are billed directly to renter. Is there a typical % that is used when estimating what the lot rent should be? 20% of total? 50% of total?

Can’t find any ads from other parks in area offering to rent lot alone to be used as comps. All ads feature the home for rent.