I left my base in the opposite direction from the deer path with clippers and a hand saw, and in the late afternoon light I found a decent copse of reasonably young and flexible saplings, perfect to be bent-literally-to my needs. I took three down before it got too late to work, and I dragged them carefully back to my base. I trimmed away the branches and cut them to length before trying to bring them into my base, where I bent them into shape inside of my larger tunnel, to slowly be reduced down to a tighter curve. I left them to sit as exhaustion started creeping up on me again, took my normal three-hour nap, before wrestling them into the end of the tunnel they would become permanent supports in, though not in precisely that particular place.
I turned and left that extension, and returned to my home tunnel to work on my next sentry-tree, as that was needed far sooner than I needed to scuttle back to my cabin without crossing the field.
I measured out the distance and direction again and started digging. My body was finally starting to get used to the endless motions of digging, and I was starting to regret the breaks I took to lift dirt back up to the surface. Soon enough, I was deep underneath the tree and was trimming more than digging. A few sleep cycles later and I pulled out my drill and started working my way upward. Before I knew it, I was breaking through the top of the trunk again, and a bright light struck my face. Without noticing, I'd once again passed through more days than I'd expected.