The unit is on the roof with no access except by ladder.

Some resources I recommend ( with 10 hrs of flying you may have covered these episodes:)PodcastsEpisode 108 - Grant Cardone...

For the lease, you'll need to be sure to get one that covers Oklahoma laws. 

The roof has an unknown age as no new permitted roof has been pulled in the past 30 years, but no appearance of roof leaks currently, but looks aged.The bank asked me to give an offer...Comps in the area have sold in the past 12 months from 110-119k, rents seem to be around $1000-1100/month

If they are all equally qualified (areas covered, knowledge about investing, etc) I'd tell them all that I'd decide with a series of coin flips and I'd tell them that you're doing that to avoid damaging the relationship that you value so much.It's a hard situation, but if you're upfront with everybody, you should minimize the chances of hurting your friends.  

Major renovations are planned: new roof, new HVAC, tearing down walls to increase HLA, licensed contractors on the premises, and some earthwork around the house to prevent rainwater drainage going through the house foundation.Thank you in advance!

My end goal is to have a passive income stream that will, one day, become big enough to where it can cover my expenses entirely.

Named Perils coverage is called that because the Perils (causes of loss) that are covered are Named in the policy. 

I'm hoping that you could take out a mortgage on the property for $50k for the engineering and if you had to sit on the property, you could at least farm it (or rent it out to a farmer) to make enough to cover the loan payments on $50k while you wait for an upswing. 

Hey I'm sure you've found someone, but If not I have reputable contractor in Oklahoma that has been in the business for 20+ years in roofing & construction.