[Shodo]

Can't think of a whole lot you could camp at that level, though I'm sure there are a few. Scryer in upper guk or ghoul magus in Unrest come to mind (can look up their loot tables on the wiki, but both are low twenties camps with +int or +mana items). You could also look up the Words of Darkness, shadowbound armor and harvester quests in Temple of Sol Ro.

A more flexible option would be to level at a camp that makes some cash (like gargoyle island then sister island in Ocean of Tears or giant fort in warsliks woods) for a few levels then buy some mid-level gear in the tunnel.

If you really prefer to farm the gear on your own (which is definitely very fun) then you'll probably have to wait until 40+ to get all or most of your slots filled in, but the good news is that it won't slow you down much as a necro.