I need some advice,

[hit_em]

My unlce has a big band saw mill, and he wants me to build him a lift to lift logs off of the trailer onto the mill. but he also wants it to be able to move around to use else where around the property. what I was think was something like an over sized engine hoist with larger wheels. Anyone else have any suggestions? what do you think would be the good or bad about my idea? I think it will be hard to monouver with a huge tree hanging off it, but him and my dad think it wont be too bad. Any suggestions would be greatly appriciated.