Also, each lender can make its own rules regarding HELOCs so there is not a standardized prescription as to what to expect. 

For that same reason I took on a 4 year lease with the physician.

Also, have a lot of physicians.

You make money here by following the prescriptions in your email - appreciation and flips. 

With regards to the Physician's loan program, you would need to validate what medical occupations qualify as different lenders could have different requirements.In your post, you mention that you are looking to relocate to the Midwest in the next few years. 

Bank of America used to have a great physician loan, but it was for owner occupants (so limited to house hack).

(Costs obviously vary not only with type and size, but also with location - just like houses).If you are not able to install a fairly basic system or you have a more complicated system with problems, I strongly suggest getting input from more than one engineer with experience in designing these things (just like multiple opinions from different physicians).An engineer that is experienced in on-site wastewater system can ascertain a lot using the property address - pulling up aerial imagery, topography, and soils data.