@Ryan Wittig, thanks for your helpful reply.
I know it seems like I have a random set of criteria but I have had to rule out many many real estate areas because of my US/UK tax situation. I can't do much in terms of rentals with a mortgage which is the natural home of so many investors.
UK law changed recently and one can not exclude mortgage interest as an expense, unless it is inside an LLC. So one can face tax rates of close to 100% on this income which blows apart the economics long term. Fine if you are super rich and own all the properties outright of course.
If I take the LLC route I open up other cans of worms (e.g. an article in the Journal of Taxation entitled "U.S. LLCs and U.K. Tax Do Not Mix!" after a somewhat recent UK Supreme Court Case on the issue).
I could investigate UK rental property within a UK LLC, but I don't want to put a penny to work here at the moment given that the country might fall off a Brexit cliff. Or everything could be fine. But the currency markets are currently saying things won't be fine.
Another option is to leave the UK but we like it here not withstanding all the above and my husband likes his job quite alot. So then, why Massachusetts for me and not some other state? I visit Mass often due to family and friends and have a fairly good grip of most of the towns demographics. There are other reasons why Mass but feel I'm droning on too long here. Why not other beautiful places I like eg France, Spain? Whole host of reasons. Prefer to just vacation there. I would love to put money to work in Colorado but it is just a bit far, I'll never get there often enough
In a perfect world I would get involved with construction inside Boston but I don't have the funds to do it myself. If I join others via an LLC, I'm back to the "U.S. LLCs and U.K. Tax Do Not Mix!" problem.
So, the gain I'm seeking to defer is larger than the amount I posted, but if I defer too much, I will then get hit with UK capital gains. But US capital gains on this are actually higher than the UK. So I want to defer, but not too much. If I push US tax down too far I just push up the UK tax. Anyways, I know it seems like tax is driving my investment bus, and that's silly, but it does matter a lot if I face rates above 50% because the treaty doesn't cover that area.
I looked at several of lots that I ruled out (E.g. one in Wareham that's in a flood zone, ones in Plymouth that are maybe ok but very car dependent). Ideally I could find a walk score above 50. I would adapt the eventual thing I would build to the market. I am just trying to figure out if it's feasible to even get a buildable lot of any kind within an hour of Boston for circa $100k. I know Brockton and Amesbury are as different as can be. I just didn't even understand what was going on with that Brockton lot--fairly large amount of acreage a 5 min walk to a commuter rail stop but with all kinds of other issues. I'm aware of Brockton's issues and I know it's very speculative. Thanks again!