A 9% cap on these buildings and high ROI.

Talk with the Nail Salon people for ideas. 

Sorry it took so long for me to respond but I think they nailed down most of the reasons already.

I think a lot of the problems you cite can be fixed or at least improved by this - ability to nail it down to better dial in on the searchers you are looking forThe above categories are confusing and have a lot of overlap and there are much better ways to do it, but I will leave it to the imagination as to why no action here has been taken..

I think @Jeremy Ellis also hit the nail on the head because it’s very important to figure out if that property fits within your current goals and strategy.

You could also ask what their terms are regarding LTV and things like that to nail down the reason they are saying you cannot get a first position HELOC. 

You and @Jay Hinrichs hit the nail on the head.  

I think most locals are aware of the history of STRs proposals/cases in Portsmouth, Laconia’s existing restrictions limiting non-owner occupied STRs to resort/shorefront only, VT's local option tax that allows a 1% tax above the state's existing 9% tax, Portland cap on STR permits and increases tied to inflation, and it's also probably a good idea for folks to understand NH's Senate Bill 249, which proposed a "ban of local bans" around STRs and basically died on the floor(?)

I've seen these situations spiral out of control and lead to occupants neglecting/damaging the property, such as making holes in the wall to look for hidden cameras, nailing doors and windows shut, etc.

If you cant nail down anything you are just rolling the dice.