What about something like a 4 step webbing ladder like what is used in aid climbing? I recently shopped around for a rescue rung and the likes of them and even looked at a few threads on the topic here and found these to be suitable for getting in and out of the boat (IMO). Particularly handy for getting in and out for a quick refreshing swim dunk or for the ladies needing a bathroom break without landing as its easy to slide right in the water and back out with these.
I picked up two of them and keep them attached to the frame on either side in a couple of small mesh draw close bags that are configured to stay put when the ladder is deployed so you dont lose the bag, then re-stuff it when done and its easy to get in and out of the mesh bag.
I imagine someone will call this out as a no-no entrapment death hazard but it really works well to help get back in the boat and its only 35$. Could probably build one of your own with some tubular and some creative knot work.. anyhow, fwiw.. here's a link:
4 Step Aider - Metolius Climbing