Water heater(s) replacement is a no-brainer.

But if you have a brand new roof, a brand new water heater, etc. then you shouldn't have to replace those in the first few years after owning.

I get copies of the water bill for the townhouse I have a tenant in.

Its in Missouri, city water and city sewer. 22 pads all rent for $700 (POH) and currently all full. 

Personally, I'd prefer tenants not hook up appliances to the gas and water lines in my units.

Trails and forest behind the house, brand new gutters, 2 year old water heater, 3 year old A/C. 2 car garage with large, built in work bench.

Trails and forest behind the house, brand new gutters, 2 year old water heater, 3 year old A/C. 2 car garage with large, built in work bench.

Another thing to think about is the high relative cost of taxes to the land. didn't used to be that way.. but county governments, water districts  have found out ways to add FEES to the land.     

Depending on the lake you'll have municipal water and sewer or you may need a well and a holding tank - can't do a spectic system near a lake.I would not build it too specific for airbnb, keep resale value in mind and follow mainstream trends.

The house just had the electrical upgraded, basement water proofed, new roof 5 years ago, newish furnish, newer windows.