I believe I was the one with thoughts on FT8. As a low power operator (I use a KX3), I've often had trouble making even 10 QSOs, under the old rules. It's great to say, "just go back to the park again," but many of the parks I've worked from aren't near my home state (I did 3 in WA, and live in VA). For my last activation, in FL, I decided to haul a laptop in and try FT8. It really saved the day, getting me half my contacts before the laptop battery started getting low.
But I have a general concern: it's hard for people to tell I'm in a park. This results in a few other concerns:
1) I'm less likely to get spotted - spots are super important to a low power op.
2) I'm not doing a good job of promoting WWFF.
3) After a little while, I'm going to show up as "already worked" for most people. They have no reason to work me a second time if they don't know I'm in a park.
I did a little testing with a friend across some dummy loads. My hope was that I could generate a "free message" CQ, replacing the grid square with "WWFF" (CQ K4IZ WWFF). Unfortunately, while this transmitted and received perfectly, on the receive side double clicking on my CQ would do *nothing*, making it difficult for someone to work me.
The FT8 message format does allow for directed CQs, things like CQ DX or CQ WY. Any two letters can be used, but not digits. My thought, to solve most of my concern, is to use CQ FF. Hopefully this would be clear enough. But I also think we should come to a concensus, so everyone uses the same format. Maybe there are better ideas!
There's also the matter of (ideally) exchanging the park identifier. The only solution I've come up with is to send it in the last message, as a free message: 73 KFF-0000. The other person has already been prompted to log by the time the activator sends this message, so it's less than ideal, but I can't see where else it might fit.