Seller finance questions

[Joseph Poluch]

A neighbor approached my Father about possibly purchasing his waterfront Trailer and would be willing to finance for up to 5 years. The trailer is permanent in the sense that its tied to local sewer and water, on blocks, lower portion finished so you don't see the wheels, deck (that wouldn't pass inspection- I believe) and an addition. 440 sq ft. according to Zillow. I dont believe that accounts for the addition. 

Our goal is to get a great deal, do some renovations an improvements (hot tub over looking the lake), new paint, fix deck. Try to make it a half Air B&B, half personal place. Rent as much as possible in 5 years then refinance... then buy the property next door following a similar concept.

... a couple questions:

Would a bank refinance on a Trailer like this? Do they see it as just another home or do they look at it differently then a typical house? 

Has any one done a BRRRR on a trailer property before and what obstacles did you face when trying to refinance?

Do trailer even Appreciate?  I have an in-law that is trying to sell their mobile home and their realtor said its more like a deprecating car then an appreciating house? Any truth to this? Could you expect buying a trailer to not retain/ appreciate in value regardless of updates?

Any negotiating tips when dealing with a motivated seller that came us first but has had two realtors give them an estimated market value? 

Has any one had any luck/ good strategies with Air B&B  rentals as opposed to year to year tenants? 

Open to any other suggestions of questions I should be asking or things to be concerned of.