Those costs still exist- Your scenario was a 250k property that with light reno which became a 100k reno was worth 500k. 

You're going to have to move both up, albeit property taxes in CO aren't bad but insurance needs to be fit for a house hack if you're going to have a bunch of tenants messing stuff up. 5% maintenance for a 5-member house hack is rather light. 

Plumbing by-passes or abandoned lines; collapsing sewer lines; badly corroded supply and waste lines (both can be from inside or outside corrosion) fixtures with very hard to find components; hidden electrical junction boxes...or non-existent boxes at junctions; outdated and/or underrated distribution panels; knob and tube wiring improperly connected to, or extended with, romex; Switches wired incorrectly, breaking the neutral instead of the hot side; no, or poor grounds for improper outlets; overheated connections, outlets, switches, and light fixtures; improper wire sizes for circuits and overloaded circuits; and plenty of others...all very costly to troubleshoot, locate, and correct individually.

I'm reaching out to see if anyone can recommend any general contractors that have experience/expertise in light rehabs for converting units into Airbnb properties.

Cosmetic upgrades including new appliances, vanities, lighting, flooring.

Property is a triplex, on the river, 150 of water frontage, lots of light maybe thinking renting long term one, and airbnb the others. 

No, their eyes dart between the clock and the road, long practice assuring them that if they make it to the second light on Maple by 8:22 they still have a change to pull into their job's parking lot by 8:39 and punch in before their 8:45 flex-time deadline passes.

I think we could probably get $500+ with a light rehab.

Check to see if you have to install any manholes, fire hydrants, curb, gutter, sidewalks, street signs, street lighting any specific street design or access requirements, Check DOT requirements for access, stop lights and permits, traffic studies, DWQ requirements for permits, permit fees and time frames.Once you have an idea of what you can build and what is required in terms of permitting and infrastructure you want to talk to some civil engineers and commercial general contractors that do the type of projects and build the type of buildings you want to build so you can get an idea of costs, time frame and requirements.

Tread lightly my friend and try to turn over every stone, have a title co. do a search on the property few hundred bucks now could save you thousands in the long run. this person does not know the bank or how much is left on the loan, does not sound right.