No problem with Bilbo being the "face" of the party, the rest being dimwitted bruisers - so much like in The Hobbit
Bilbo need not fight - he can taunt the enemy (remember ettercaps in Mirkwood?), throw rocks, etc.
Here Bard would be the best class. As Bilbo should have "Noble" as background "entertianment skills" senso largo are up his alley. Story telling, singing, playing an instrument - that's what the aristos do when they meet for tea, scones, tarts and plotting the subjugation of the working masses.
