You will have to bring in 60 homes to hit 80% occupancy. If you can bring in 1 home a month and sell it, that will take 5 years to accomplish. On top of that, you need at lease one to three years of stabilized financials to make the lender happy. The bottom line is that your 10 year request is 100% reasonable in this case. You might be able to scale back to 7 years and be O.K., but 5 years is just too short on a deal like this. One solution might be to have the right to “buy” a 5 year option at the end of the fifth year by paying down some more of the principal in one lump – like maybe $50,000 or so (whatever you can negotiate). Your worst case scenario is if you fail to get the park up to stabilization by year 4 (it will take a year to get the loan) and then default and lose not only the park but all those homes (sure, you can move them, but you’ll lose a ton of money no matter what).
Don’t let the seller get you into trouble here. You’re doing him a favor buying a park at 50% occupancy and he needs to appreciate that. He needs you as much or more than you need him – trust me. Win/win means that both parties respect each other’s needs, and he’s not doing that at 5 years.