Interesting the two classes OP has played as I'd put Necromancer at the high end of upkeep/prep and Bard at the low end.

As a bard you are looking at finding defensive/offensive staves, pills, orbs of travel, curing items, and potions. Though you already have some abilities that bolster these factors and you need to rest for mana. Artificial cool downs only come into effect if you are dying, I can't think of anything else that would slow this class down, versus the artificial delay in playing creating by cool down on creating/gathering zombies. The only way to cut some of the maintenance down from playing bard versus another class would be to be in a cabal that gives you some benefit you would need to gather preps to have if you want to be less reliant on offensive - Empire, defensive - Fortress, Battle - combat preps, Outlander - AI benefits (not sure how much time is realistically saved as Outlander)

The only classes that could have marginally less prep time than a bard and effectively explore would be an empowerment class playing a race with high regen. If I had to pick one combo that combines those two I'd say paladin champion elf. A big part of how well this would play out for you as any paladin would be your virtue(s). If you havent played an empowerment character previously, I'd suggest Whiysdan or Baerinika as an imm choice.

I'm not playing right now in large part due to this type of frustration with CF, the down/prep time versus the amount of time I would actually spend playing. Can you play without shield/stoneskin/aura/haste(ish) preps and sub optimal gear? Sure. Can you beat expert players in PK without these things / defeat area explore creatures holding highly limited gear? Not likely.