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%).

It's good to have developers who have experience with container building but not a hard requirement since the installation isn't too complicated and would get help from the factory who make those container homes as well.I've been working with container manufacturing company who build 90% of the unit (prefab) from Vietnam and ship to the US.

Too few details to answer (Of course this varies county by county, all questions could be answered by reading the (zoning)/building code and/or clarified with a visit to the county planning office).but some clarifications because: lots of things are "tiny homes" but what you describe small houses "on permanent foundations" needs to be clarified , tiny homes could be:-stick built, see below. check your county code/planning dept-stick built cabins/recreational, a specific zoning and potential occupancy/etc restrictions but worth looking into where the zoning allows for it -hud manufactured homes (smaller singlewide perhaps 400sq ft 600sq ft minimum)-non-hud park models (on axles), ansi standards- other "RV's" built on a chassis:  organizations, state agencies, etc - will certify factory built (or sometimes inspected professional built) tiny homes on chassis - to whatever standards ansi, riva, dot/ l&i?

@Jim K. had to unlearn blue-collar poor upbringing of, "get a good job and work hard to be successful".Parents meant well, but had limited education and they grew up poor working in factories. 

Tesla is building their new semi-truck factory next to their battery factory, Microsoft, Apple and Google are investing millions into data centers.

There's lots of factories/warehouses out there so heavy demand for rentals with the employment going on.

I've never managed MTRs before and would love any advice on other rule changes that should be adapted and/or any other factor I should consider, particularly through AirBnB.

@Henry Clark I think getting over the trust factor is the biggest barrier to clear first.

The last factor is what makes it "worth it" to you...an extra 5% or 50%. 

I started working in a factory at 18 worked my butt off and made something of myself.