Thanks for all of the replies. I thought I would consolidate my responses into a single message.
sui generis, the JMT might be a better choice than what we're planning but we want a significant forced separation from work. I have been a late-days-and-weekends guy since 1999 (the series of implosions in the valley really hit me hard and my response was to become indespensible; this is not without it's costs) and my wife, a contractor, has been very similar. We are very very uncomfortable with being nomads but we kind of want to do it for that reason; you should spend some time being uncomfortable now and then.
DreamFire, thank you for the link, I will look through it. As you I am concerned about the future of ACA; I have two pre-existing conditions which require no treatment or prescriptions but which under the previous regime might have been gotchas for insurance, especially in the ugly issue of recission.
On nervousness, I am genuinely concerned mostly about imminent recession and healthcare costs. Healthcare looks like it will be around $1000 to $1300 a month before subsidy in many of the places on our maybe list; healthcare has been growing above inflation for some time and that's quite a serious cost even though it will be lower with subsidy. The other thing is, selling a house in the bay area will amount to a non-trivial part of our net worth. Research shows that most of the time, on average, you are better off investing the lump sum right away, but no one lives averages and it's very very hard to consider investing all at once when a recession looks iminent.
Miss Piggy notes similar concerns about the economy. What goes up irrationally tends to come down. Once the chinese money stops flowing into bay area real estate, for example, or australia, vancouver, ..., things are sure to crash again.
Trifele notes the Doctor Doom posts :-) yes I have read them. I think he's a fine writer and got something out of his posts. I wish he'd post something more recently. An ongoing and nagging observation for me is that many many many of the FIRE bloggers are either not RE (monetized blogging), are pending RE, or are just recently RE and often in an unsustainable manner (kids living unsustainably and ungrounded, etc. - lifestyles that will become problematic for almost everyone in the long term), etc. It would be very comforting to see stories from people who have done it long term without a pension on the side, for example, who really rode the market.
TartanTallulah - good points.
Eric mentioned bonds. As it is now, we plan to go with a rising equity glidepath; though it is interesting to me that BigERN is not actually doing that with his portfolio despite being the reference for SRW and models for dealing with market downturns in the first few years of retirement (but that is, as like the examples above, because he is not really RE in the sense that he is becoming a full time options trader; I'm not retirement policing but it's interesting to note). If anyone has not read his series on safe withdrawl rates, and in particular some of his critique of Kitces, it's worth a read (
https://earlyretirementnow.com/2017/12/13/the-ultimate-guide-to-safe-withdrawal-rates-part-22-endogenous-retirement-timing/comment-page-1/ and so on ).
I will say reading ERN SWR blog postings is one of the areas that gave me peace of mind. For one thing, his toolkit (part 7) is much better for doing concrete analysis than cFiresim; for another he is one of the few people making the point that target-portfolio-minimum based timing is extremely dangerous because it tends to concentrate people at market tops. We could have pulled the trigger two years ago but the same thought had occurred to me so we did not.
Anyway, thanks for the thoughts.