Troll assassins are tolerable for ultras since assassins have lower level requirements. Other trolls require excessive wishes to ultra. I haven't tried a mist elf ultra, but their xp requirements are high and might have similar, though not so severe, problems.
Black torc is not necessary at all, IMHO. There are lots of artifacts available, especially with the larger number of greater vaults in the game. The extra PoCC doesn't matter either because corruption is basically a non-issue in current versions. You'll be swimming in SoCR by the endgame.
Boars can only be found at level 15 or above on forest tiles. IIRC, they drop skulls at a flat 1/3 rate. Of the ultra requirements, the skull is generally not that big of a deal to find, IMHO, compared to the AoLS or the scroll of danger.
A few other considerations:
-Beastfighters and, to a lesser extent, duelists have a more-annoying-than-average fight against Andor Drakon because they can't wield the ToTRR effectively.
-Thieves likewise have problems because their stunning class power makes him teleport randomly and forces you to chase him (unless this was fixed?)
-Ultras require some alignment shifting which may cause problems for chaos knights.
-Drakelings have problems in the Ice Queen area. This isn't a huge deal, but having early access to the greater vault in the frost giant caves is a great place to try to get a wish/AoLS for Khelly.
-While I generally prefer the shorter-lived races for better starting toughness, for an ultra where you may have to mess with a lot of pools and whatnot, having a longer lifespan is not a bad terrible idea just so you don't have to worry about aging. Consider a dwarf, gnome, or elf.
Hoping to win with every class, doomed. Archer, Barbarian, Bard, Beastfighter, Druid, Elementalist, Farmer, Fighter, Monk, and ULE Priest down.