As this became a warm-to-hot topic I let the thread die for a while.
Update: Decided to go for it.
Have worked up to being able to ride 400k in brevet-allowable time though none of it on official brevets. Going to try a self-designed and self-supported 600k route next week/weekend (weather-dependent). Based on advice from here/around the web/various forums and blogs, I'm not going to do any training rides further than that. I may make one 4-600km out-of-state ride in a rolling hills area in late June/early July just to test myself over that terrain, but other than that, I've been riding locally on near tabletop flat terrain because that's what's available/affordable.
Airplane Ticket bought. Passport renewed. Still researching international medical plans/costs (they're both more inexpensive than I thought and cover less than I hoped at one extreme and are outrageously expensive and still cover less than I hoped at the other so far). Bike's in good shape. Replaced a set of tires, a chain and a cassette due to all the training rides. Working out the logistics of getting the bike and spares/supplies there as cheaply as possible yet on time. Luckily, I have another recumbent I can ride while the "brevet bike" is enroute if it doesn't travel with me.
In case anyone cares/is wondering, I'm riding a Bacchetta Corsa, med/large, 650C.
Back to lurking/riding.