And I generally like to have a longer ride before a LONG ride. So before my 600k last year, I had a 200 miler. And my long rides this year built up on one another in rando fashion 200k, 300k, 400k and then a couple of 200 milers.

I'd suggest you try to at least get in one 200 miler (or 300k) before your 267. Especially if the course is hilly. You'll also want some time testing lights, and riding with lights. With a hilly 430k, I imagine you'd have some time riding in the dark, and being comfortable with that by training in it is invaluable.

So how about starting your LONG training ride well before dawn, so you aren't spending too much more than half of a daylight day riding your bike, thereby alleviating the family missing you too much? That assumes you're in an area where it's safe to ride at night - even doing short loops of a dark-safe route, and then tacking on a different route when it gets lighter would work.