Make sure you know where the guard rails are with your bank. 

If it's worth that much, taking a HELOC on it should not be an issue at all long-term or short-term as long as the bank will do it.

He is very good about deductions on tax returns so his income looks negligible and of course banks wont talk to him about loans.

-Local banks were the best.

Any local bank that does this kind of financing should be able to approve you as long as you have a good enough credit score and never declared BK.

Or are you actually talking to a bank about buying the note so you can see the notes and credit on the owner of the property?

I contacted Buildium and they confirmed they do not offer credit card tracking, but offered a workaround which was to set up a credit card as a bank account, and when there is a balance it's just always negative in the bank account, and this would allow you to track individual purchases like it was a checking account.  

Could be different if you are working with a bank that do not sell the loans they make 

Most banks I work with require anyone with over 20% ownership to guarantee the debt but have seen as low as 10%.

You might find a local credit union or community bank that will go to 95 -100%.At one point I called 2 different VA Regional Loan Centers regarding this section in the VA lenders handbook:Assumability - The second mortgage should not restrict theVeteran’s ability to sell the property any more thanthe VA first mortgage.