She is not in a position to lend a personal loan to me. 

Many Realtors will suggest purchasing a property using a FHA Loan, to reduce your out of pocket money.

I was last getting terms around 5-6% for the first 5 years, then floating with prime, 20 year term. 

The best option would likely be a construction loan, which can cover both the purchase of the land and the build.

.: Quote from @Jennifer Turner: Has anyone ever sold a property with seller financing then later extended the repayment period or modified the terms of the loan with the buyers?

However, there are other loans designed for fixer uppers referred to us hard money loans, bridge loans, or fix and flip loans but whatever you want to call them they're essentially short term, interest only loans with no prepayment penalties designed to finance a higher % of your purchase price and typically all of your renovations not to exceed a certain % of the ARV (typically 75% max). 

If you have any loan questions feel free to reach out. 

Reason being HML's are typically short term loans that are interest only.

Long term $ can range from 6's-10% range depending on all types of factors - LTV, location, unit count, debt coverage, borrower strength, full doc or lite doc programs, etc..

If that's the case, you'll want to start with a fix and flip (or hold) type of loan, complete your renovations, get it rented out and THEN refinance into a DSCR loan for a long term hold.