casters on a Producer's Pride 8x8 coop

[chickenmuggget]

I'd like to put a swivel caster on an 8x8 Producer's Pride Walkin coop. Dimensions are 8x8 and it weighs 250 lbs. I want to mount the caster so that it is outside the corner with the caster to the side of the coop and not directly under it. Any recommendations or experience with this?

 

[aart]

Please post a link to the exact product you have.

I'd first question why casters on such a large coop?
What kind of surface(s) will it (hopefully) roll across?