I bought a used Vagabond which had the metal Wenonah drop plates. The previous owner had used bolts that were maybe an inch too long, and left the nuts at almost the end of the bolt. So the seat could lift about an inch to get feet under for kneeling. Once your body weight was on the seat, it seemed to stay in place pretty well. The seat does jostle a bit as you lift the boat to your shoulders for portaging. So, IF the issue with sitting height is just getting your feet in and out, that could be a solution. (But this might not address tketham's needs.)
One could hypothetically also make little wood inserts to slide in between the seat and bracket to lift the back edge of the seat, or both edges, while kneeling. But, the simplicity of the set-up was nice, as was the lack of any additional parts other than slightly longer bolts, although the whole thing was kind of janky and jangle-y.
One could hypothetically also make little wood inserts to slide in between the seat and bracket to lift the back edge of the seat, or both edges, while kneeling. But, the simplicity of the set-up was nice, as was the lack of any additional parts other than slightly longer bolts, although the whole thing was kind of janky and jangle-y.
