Thanks; that's very helpful. I think it does make sense to use the 10-3 UF-B wire for the underground portion. I'll transition to THHN in conduit for the portion under the deck and beside the building.

I read that a disconnect is required for each building, (farm wiring) but I don't recall ever seeing that in a shed/detached garage. Is that a requirement and if so can I use a standard toggle for the disconnect?

Thanks again.