(we'd write a dog security deposit equal to that cost into the lease.)

Security deposits  

In Washington moving a single wide was about $4-6k and a double wide was ...well about double that. 

In a smaller scale, this is why landlords try to collect as much money upfront as much as possible (e.g. security deposits, first month's rent, last month's rent, etc.). 

I don’t mind paying a fee once I secure the lending. 

its 60 wide 40 deep... big sliding doors  electric doors can cost a bunch..

The property must be the only security for the loan.

For example, find a secured loan @ 12% for 12 months or less. 

Form an addendum that Jack and Jill sign where Jill acknowledges she will be taking over for full rental payments, damages to the property, and security deposit (would not recommend giving half back to Jack you could argue this would cover him getting of his lease agreement early).  

So maybe by doing it outselves will be a better option with the help of subcontractor, the next time.The reality is that I am the one intereseted in not losing money because is my business, the contractor does not have a problem with the time, he has his money secured.