If you are looking for a PM for lower to medium priced rental properties I would start with Nimius; they have adjusted to those challanges.

Don’t worry, however, this is adjusted accordingly with comps (similar 2000sf GLA properties with a 1000sf basement are better than 3000sf GLA properties with no basement, for example).If the appraiser did get it that wrong, then you do have some options...

The climate is ideal for the plant, and land will be at a premium once hemp production is industrialized.

A blanket mortgage as@Wayne BrooksMentioned is going to limit you and the rates will most likely be higher and adjustable or have a balloon payment. 

Two of the common areas of concern for HELOCs I see out there is the 10 year maturity date and the adjustable rate.

Residential real estate that doesn't consume more than 1/3 of the median household income in well-located cities with diverse economies and generally temperate climates will always be in demand. 

When selling stocks it’s possible adjust whether selling older or newer shares (first in-last out or first in-first out) so one can effectively choose to sell shares that have more or less capital gain associated.

Adjust your criteria to something a little less main stream/common.

The important thing is that you evaluate your goals for what you want your real estate to do for you, and then adjust your criteria and approach to align with those goals.

I would only refi when the rate differential made sense, to avoid an unfavorable rate adjustment, or to remove PMI (like with a FHA loan).