^^^^ but you need to be able to drive in a tractor with large spraybooms deployed!
(most of these Ag. buildings are "clear-span," anyway. there are several farmer and tractor-orientated publications that carry ads for these, ...steelwork kits are usually 2 uprights and 2roof-halves per portal-bay...bolt together at eaves and ridge, hoick upright and bolt feet to prepared pads.....purlins often timber, -should be cheaper to source locally, or use z-purlins.....do not skimp on the roof ...remember the snow-loading can be very high up there!.....It.s possible that they will make a frame with steeper pitch for the roof and the saving having low sides, would probably even-out the price....plastic-covered box-profile sheets at a steep enough angle,should shed any reavy build-up.
obvious, (but not! ) ridge fore and aft! you don't want ~100 cu.feet of snow to dump over the entrance!.....allow width to top and tail aircraft without fouling stanchions or doorway.