I just did this rear table mod with a wooden dowel I had.
Filed the dowel so it fit all the way into the plastic base, then took a large washer, maybe 1" or wider and used a drywall screw to hold the dowel tight in the plastic base. Bolted the base and top supports back into place with the dowel reaching almost to the curve of the metal table bracket.
Went camping with it this weekend, the table rises up like magic.

T Hawkins
88 Westy