You’d need to calculate how much area you'd like them to have before building. I’d be inclined to use something, maybe hurdles and see how you and the chosen few feel about being in a small area and how much pasture they actually need for 12/24 hours.
I reckon you could do something cunning and less intense with electric fence and some solid posts. I think it could be arranged so you’re only having to move one bit of tape a day and not much wee posts, (or two tapes if you want to clear them off the previously grazed section). In my attached pic, I’m thinking the perimeter fence line would stay for 5 days, only the dividing section(s) would need moved along. Then they’d get moved into another chunk and the new perimeter fence set up to allow easy daily movement through the next few sections. If that makes sense? Also have the option of allowing them access to larger plots if needed.
From the growing trees perspective, my concern is the risk of a sheep getting free in any system or deer coming in and damaging trees, young fruit trees in particular.
Depending on what you’re planting, a 1.5-1.8m regular plastic/weld mesh tree guard and fence post stake (rather than a 2” tree stake) might provide both a suitable protection for your tree and secure anchor point for electric mob grazing scheme. But obviously not suitable for fruit trees on dwarfing root stocks.