Okay, I was dying to know whether shelters were in the game or not. For anyone else who is wondering, they are available, as revealed in comment number two.
I am not sure that your conclusions are all correct. First, you say you are building an engine, and the strong trashing and good payload are definitely there to do this, but... the most important thing for an engine is the draw, and it's quite lacking here - particularly when you see the only village is squire, which prevents you from actually using the normally quite-decent-for-this-purpose steward in order to do more than spin your wheels unreliably while producing $ very very slowly. Given any smithy or village, I would probably agree with you. But the only way of actually getting increased handsize is... apprentice. You say Apprentice/rats, but it is actually apprentice/anything-costing-3-or-more. If you are going for the Apprentice/Rats plan, then you have to have lots of rats actually - you need to collide apprentice with rats, probably first, and then have another rats around WITH a junk card in order to replenish your supply of rats (and if you are not doing that, then you might as well just buy whatever other card is available). All of this is really finnicky, particularly just getting the cards you need to be together to both be in your starting hand of cards. Beyond this, you probably have to do this a few times per turn in order to get any reasonably large multi-goons turns going on. But realize that you are going to have LOTS of dead cards in your deck - excess rats you don't want to play, and goons and squires don't draw either. This puts rather a lot of strain on those apprentices to do lots of work (especially as you realize you are going to get goonsed reasonably often - if not all the time - by almost any opponent), and again lowers the chances you get apprentice-target in your starting hand. So that is a lot of set-up time, and of course multi-goons is big payoff, but how big are we talking here?
Okay, so you want an alternative. Basically, the one that seems possible to me is a fairgrounds-based attempt, as the game will be slow, and it seems that there will very likely be enough time to get them up to being worth 8 (this is why I want to know there are shelters), and grabbing lots of them. We want to open steward for copper trashing in this plan, probably squire really as well, and get goons, baker, and treasures early, then fill out the rest of our cards, one province, and go after the fairgrounds.
Of course, probably the big goons plan is a bit better, but you have to know which piles to go after - probably 3 of apprentice, rats, squire, goons. And go after them fairly aggressively. Because I think the deck is too finicky to get as much as triple goons on a regular basis (even double is stretching it). And I don't think it's immensely obvious.