[StageHand]

Will brifters work with V- brakes?

No, not really. Just the travel agents, which as you said leave something to be desired. But they work.

I thought about bar-ends but I've never used them, will they work with the flare of the dirt drop style bars?

Yes. I think dirt drops would work better for you than the Bell Lap bars, since they have shorter drops, and it's easier to reach bar end shifters. If you end up using STI shifters, than go with the one you find most comfortable. For optimizing performance in the dirt, use dirt drops (WTB, On-One, Origin-8).

Another option is trekking bars, which are essentially, two flat bars, one is just higher and farther away than the other.

Components are low end shimano, I have another bike the the shed I might scrape some parts off, that's where I was going to get the cantis.

Wherever you find parts, choose them for durability and toughness. Bar end shifters will be more reliable than STI levers, for example. Thumbshifters are less likely to jam/break than trigger and grip shifters (though I've seen it happen)

Oh, and have fun.