I'd suggest using landscaping timbers and rebar to contain the gravel.
The timbers are relatively attactive and rebar stakes through drilled
holes in the timbers are all but invisible. As for spreading dirt or
gravel, tractor with box blade or a Bobcat is probably the best way.
You can move a lot of dirt with a Bobcat (but it will beat you to
death). I'd recommend putting the poles for your barn in first and then
build up the timbers and fill with dirt or gravel. Make sure the
poles are rot-resistant.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.