Nothing fancy, but I keep a homemade portable standing bench at the farm house so I can check zeros. It's not solid like a traditional seated bench, but I can easily move it around and it closely matches my zeros for field positions shooting off-hand, kneeling and sitting.
I have a lightweight portable target stand that holds a cardboard FBI Q target backer and I stick it out to whatever distance I need. I use a compact laser to verify distance and there are fields around the house where you could shoot out to a maximum of just under 1,000 yards if you cared to do so.
Here's a three shot group from 100 yards off my standing bench. I'd expect my handloads from off a solid seated bench to be even better, but the standing bench works.
Later