Absolutely, a whiskey barrel would make a great bog garden. W/ the little rainfall you have I would line it and have a ready source of supplemental water, you say you have a pond so pond water would be fine. Sarracenia purpurea and it's hybrids, Drosera intermedia, even Dionea if well insulated and mulched also many native orchids would thrive in a zone 5 bog in full sun. I would still insulate the exterior and mulch in winter.

Generally speaking there are two types of "bog" people make. One is a "true bog" that is full sun, nutrient poor, acidic and has carnivorous plants, orchids, etc. and uses mostly peat and sand as a medium. The other "bog" is nutrient rich, uses soil or muck as a medium and contains marginals like cardinal flower, blue flag and many others. A whiskey barrel is appropriate for either, just remember a container will always have much greater temp fluctuations than anything put in the ground.

Good luck! Have FUN!

Thanks for the information. Now I will have to get busy and try to get this done.
debbie