So after the last failure at transfer images onto the clothespins, I tweaked the process a little and came up with something a little more predictable. It still didn't turn out exactly as I would have liked, but again some learning took place which is all I can ask for. Here are a few pictures of what I've been doing and some of the results.
The product I've been using is Golden Acrylic Matte Medium.
I put a couple coats of the medium on the surface of the clothespins and let them dry. This helped create a barrier between the absorbent surface of the wood and the layer of medium that would suspend the ink being transferred.
I used a fairly thick final layer of medium before I pressed the inkjet transparency paper (with printed imagery) onto the clothespins.
After allowing them to dry completely (overnight) I was able to peel the transparency paper off (carefully) and I was left with a pretty clear images.
In hind-sight, I would have extended my layer of medium to cover the entire area of the clothespin so that the method wasn't so overly obvious.