Just found a 4'10" Placebo surfskate in a surf shop and it fits!
Big Winds (great shop in the Gorge) confirms that the Naish skater 4'8" fits. That would be my first choice but the price is still way up there for a niche board.
The North Skimfish is still up in the air. The North Nugget would be a more fun (and pricey) choice, but it's 5'0".
Going to test a 4'8" and 4'10" sweet potato tomorrow, may purchase.
For reference the Placebo is 4'10" x 19.25 x 2.20
while the sweet potato is 4'8 x 20 x 2 1/8
and the other sweet potato is 4'10 x 20 1/4 x 2 1/8
2 cool custom surf-specific shapes by local shapers here are the fartknocker
by Stewart Surfboards in San Clemente, and the tombstone
by Infinity Surfboards in Dana Point. They can both be shaped to 4'10 with a stub nose and with thick glass.
I know a local with a cool splitboard-type design, maybe he'll post here.