For fun while back packing or maybe even intimidation of a two-legged aggressor, a .22 is fine. Revolver or Auto, they're both fun and not too obnoxious in use. (Pic below: M-18 Smith in .22 LR...their model 66, 67 and 69 in .39 spl, .357, or .44 mag are virtually the same weight ~38 oz.)
2nd Pic: Smith M-63 & 60 with 3" bbl's. One for fightin', one for fun!
But for real protection, a centerfire is better.
3rd PIc: a foursome of .357's, none of them particularly light weight, but all would do the job: 3" M-60, 4" M-66, 5" M-27, & 6" M-19. Smith still makes IIRC, a M-69 in .44 Magnum that weighs the same as the M-66 in this pic.
I'd gladly pack a duty sized revolver for most anything in the lower 48. A .357 packs plenty of punch and can be had in 8 shot variations for those convinced that capacity matters. If the size and bulk of a duty size piece concerns you, get a M-60 Smith with a 3" bbl. and be happy.
A .44 magnum suitably loaded will do for most any thing but the weight (necessary for adequate DA control) becomes a factor.
Question is, are you more concerned about the extra two pounds of weapon weight, & if so, carry nothing at all and depend on the odds going in your favor. But if the danger potential is realistic, either rearrange your hiking itinerary or carry something that'll do the job, and the extra weight be damned. Best regards, Rod