I  buy several million in umbrella insurance on top of landlord insurance, have tenants buy renter's insurance and use licensed contractors only.With the LLC, for most people it would be single member or a couple, they'll sue you personally anyway under the "alter ego" theory.

Slight modification of facts and circumstances (so subtle you may not see it, but a talented CPA will) can, will and does alter the response.Publishing YOUR answer does not mean you are publishing THE answer.

I think maybe two a year is more than most landlords do but do whatever you're good with you can always alter your schedule later

It could be as complicated as some design issues or as simple as gearing their expectations and altering your marketing.I do see it is not a traditional triplex but converted.

If they are on a budget, I am really great at finding free things and deals, so my time could translate into savings for them.

To name a few:Wall modification and drywall patching for new ductwork locationsFloor plan modification - You will need to build-out of mechanical closets to house the furnaces for each unit which will alter the floor planA/C - Not sure what the existing cooling system is, but the new heating system could effect the cooling systemElectrical - May need new electrical panels to accommodate the furnace load, & wiring to power the new furnace unitsWith that said, I think this could easily cost over $5,500 a unit when you consider these additional scopes of work.I would highly recommend getting in touch with a local HVAC contractor who can provide some insight on the construction considerations & costs as apart of your due diligence.

It costs me significant money & time (and in my line of work and specialty of IT consulting, that directly translates to $250.00/hr that I could be doing instead) because some other crappy landlords haven't been doing what they should.

Are they tough on illegal units and/or alterations without permits?

We could sneak around and take photos with telephoto lenses of anything and everything, as long as we did not alter the landscape or break the law in any other way.  

Sincerely YoursMr Wholesaler Sadly, this is probably a truthful translation of 90% of those.