Welcome to Dakka. Enjoy your stay.
I think your best bet is to try and get one of this version of Bilbo:
A: It's plastic, so will be easy to convert/repose should you need to.
B: He comes with a walking stick carrying arm in a more upright pose, which will be easier to convert to a barrel-holding pose.
C: he is part of the starter set, so you should be able to pick one up pretty cheap on ebay. Even with the rest of the dwarves thrown in (nice models in their own right) it should only set you back a few quid more than buying a resin Bilbo.
Hope that helps. I'd also encourage you to share progress on this project on the forum, it sounds interesting. Are you going for the orc/elf battle at the side as well, or just the barrels?