[Squirrelloid]

I've used GK with plenty of nations, often UW ones! He's a great expander early on against non-archers non-mages - which means UW you can guarantee a province/trn so long as you avoid the hydromancers (they're the ones with sea trolls and a kraken). Land nations need to be a little more careful (or give him air magic!).

Jomon:
1) Samurai armor's huge encumbrance is irrelevant. If they acquire more than 20-30 fatigue, you're doing something wrong. Namely, not killing the enemy fast enough. You have 6 damage katanas as the *low* end of your weapon options. At the high end you have 10 damage glaives. Since all the units you will ever buy have str 11, that's 17-21 damage per guy. That's enough to really matter against even elite infantry. Throw on some strength of giants and its your own fault if you start fatiguing out.
2) Earth bless can make a lot of sense as Jomon - specifically for your summoned thugs. But it also benefits your sacreds - the yamabushi are well worth using *even without a bless*. Don't overlook the H2/H1 thug that comes even earlier than the other one - he can self bless and has only slightly worse stats. (Also, only requires E gems iirc, instead of precious astral).
3) Jomon's magic is good. No seriously, you have access to everything but D natively, and you have a summon that has D magic (i forget which offhand - its the swamp one). Who cares if they're not sacred - they're dirt cheap for how good they are. 4 total paths for 160g and recruit anywhere is pretty nice - it comes out to around 11g upkeep, which is less than 2g/RP in upkeep - its not winning any efficiency awards, but its certainly not notably bad either.

And since you can (and should) buy a lot of them, you'll have the path combinations you want, and access to boosters in most paths. The only boosters you won't have reliable access to are air and fire, and for the most part you won't care. Heck, you have the coveted E+S in combination, so you can make coins to S-boost. IIRC, you can get to RoWs without needing your pretender involved.

Site search aggressively (you'll be able to use auspex, augury, apsu, arcane probing, gnome lore, and haruspex trivially) to get good gem income.

Map move 1 a problem? Use your air income to make boots of flying.

4) Samurai archers suck. No seriously, don't buy them. Go-hatamoto, aka-oni, ashigaru, and yamabushi are about the only troops you should ever buy.

5) The monks are just amazing, but not for research. They're less efficient researchers than your other mages (no seriously, they've got half as many RPs for more than half the cost, meaning they cost more upkeep/RP than the mages do). What the monks excel at is being handed a master matrix, and leading line-backer communions in which they get to use awesome spells (W+N monks), or casting AoE air shield (A monks) on your shield-less troops. The F and E monks are acceptable researchers, and the cost of getting the really awesome monks.