@Neal Collins I work on Transformers. you know Autobots and deceptcons... jk Not the ones on power poles, I work on the big ones coming out of power plants.

Spokane, Wa suffers a lot as a result of the Seattle-side government. 

@Harrison CookYour post kindles lots of questions.In the "good old-days" most heating systems were vastly oversized for the building they were heating - energy was relatively cheap, insulation was non-existant to poor ... so it was easier and safer to {drastically} oversize.Today, while energy {in North America}  is still relatively cheap for the moment,  we have a much better understanding of how to make buildings more efficient {though you might not think so looking at the construction industry in the U.S.A. and Canada}  and there are often more cost-effective measures than simply replacing an old, over-sized heating plant with a new, over-sized heating plant.You really need to - or at lease should -  perform a heat load analysis to properly size your heating system, a component of which, is determining the rate of heat loss of the building envelope.  

If you're wiling to suffer through, then you have those benefits at the end of the day, and at least you have your foot in the door of real estate. 

Give us the answers to the questions that @Michael Plante asked and we could better help. 

That means that our options are either to let the lease expire naturally, or to evict the tenant for violating the lease for smoking pot inside / covering smoke detectors and risk having them become a tenant at sufferance or destroying the property.

Right, but I don’t want to evict and risk property damage or for them to become a tenant at sufferance living for free for 6 months.

@Michael Plante Check with the mobile home dealerships in the area as well as your local manufactured housing association.

He was a self-taught engineer who founded a company that built plywood plants all over the US. 

Working class neighborhood next to a plant or factory, maybe?