[melli]

Thanks, What would be the copper option sizes?

Just google voltage drop calculator...Southwire has one.
You can enter in aluminum or copper wire of varying sizes to get your max Vd. Up here, from meter base to house, max Vd is 3%.
5% might be allowable down south.

And as far as conduit vs direct bury, I am a fan of AWCU (direct bury armored jacket aluminum wire). It is cheap, even though you have to go a size or two higher compared to copper, at least it is affordable (copper in heavy gauge is expensive and we used to have a problem with thieves pulling copper wire as the scrap value is high). I like ACWU because I can just dig a trench of chuck it in...on the other hand, installing a conduit and pulling wire is a pain.
I had a similar deal to you, except 250ft (200amp) from meter base to RV, and another 100ft from meter base to pole (which I have to include in calculations). Then I may want to go another 120ft to another building...

I do like TroyT's suggestion about calling power company if they will give you size of cable needed (save a lot of headache).

http://www.ecswire.com/products/specs/acwu90