I have done this twice; both times with 1" Poly pipe. For the barn: I ran the poly line from its source, in the basement, to the barn below the frostline (approx. 45") at the barn I installed a frostfree hydrant. Done deal, six years no problems of any sort and no winterization necessary. To the shed I ran poly line approximately 18" below the surface, with a pipe puller, this line gets blown out in late October. four years no problems of any kind. Leaving poly pipe pressurized is a point of contention for some as are it's flow characteristics. Works fine for me.
You could probably go for schedule 40 and fill your bucket 30% faster, for only four times as much $, but why?