Calculations say I can add a 1bd/1bath, 400 sq. ft. cabin with hot tub for $125k all inclusive.To the loan officers, between my mother and myself, what are our options to acquire funding based off the equity of the land without having high income?

Licensable vacation rentals are obviously in high demand and offers can become quite competitive, I don't have any formal statistics but I'd say a quality active or eligible vacation rental sells at least twice as fast as a non STR property, the majority within days..My best advice to investors shopping for a hot or high demand asset class is:- Prepare & Practice: Get your ducks (GO UO!) 

Another idea I had was to just use standard research out there on building systems like the air conditioning, wiring, plumbing and so on, to estimate how much time they would normally take to require repairs.Here's a paper that discusses "energy modeling" for single family homes that is pretty recent that is an example of what I'm thinking of:https://www.mdpi.com/1996-1073/12/8/1537 

An AFCI  device senses the delta between power and in neutral in an attempt to detect an arc that's bridging air space.Most AHJ'S here now require pretty much every circuit to use a AFCI/GFCI combo breaker.Those retail circuit seekers (tracers) from the retailers aren't very good, a good budget one is north of$500, good one's are $1500-$3k

Will be listing at $425k, we are looking to upgrade to lakefront.Here’s my air BnB listing for some pictures https://abnb.me/lggVYb60xvb

This area is hot due to it being close to downtown.  2.

you can get a mallet that helps get the air bubbles out and keep things level.  

Upon personal inspection, I often find terrible workmanship.For example, I saw a "newly renovated" property advertising it had central air.

I think this is going to be a hot topic for many given that the big driving factor is the low rate we have on the old house (2.7%) compared to our new house (7.1%).

We acclimated the flooring, but I suspect the existing tenant may keep the house at some very different temps (when she travels I suspect it's quite cool in the winter just warm enough to keep pipes form freezing, and very hot in the summer).