I've been following the TV show, Digging For Britain, and one of their episodes featured a cavalry re-enactment group. It was amazing to see the lengths to which this group went to make everything absolutely authentic! They travel around Britain, doing re-enactments for different events. You can see a video below.
The re-enactment group begins its thing at about 44:35, though there are interesting bits about the group and the Roman cavalry's gear interspersed throughout the whole video.
The archaeologists digging up forts that had a large cavalry presence had a hard time figuring out just how the horses and soldiers were quartered. Eventually the figured out the soldiers slept in the stable, with their horses! There were pits in the floor to help deal with the horse urine and drain it away! Having worked in a riding stable, and knowing how foul the stable smells first thing in the morning before being mucked out, I don't envy them!
Edit: there's a section specifically on Vindolanda that begins about 35 minutes in.