Sorry for your loss (I never heard of the breed before, they are beautiful dogs)
The guiderails aren't really ideal for this application due to their (lack of) sturdyness, but if it works out it's less stuff to carry with you.
You could mount a small piece of plywood to these brackets:
multiblades kapex brackets And adjust the height so it will be flush with a guiderail on top, if you make the plywood a bit longer than the bracket, you can then attach the guiderail to it, with a T-bolt and wingnut, or just use a railclamp.
Same principle for the leg: you can make a simple adjustable leg out of plywood, and screw a flat piece on top for a railclamp.
I was thinking about
limitstops for the stopflags, but they ride on the wrong channel to be usefull (but maybe they can be modified, or frankensteined for the knob and glidenut).
If it doesn't work out, the multiblades brackets look like a good base for plywood extentions with a kreg rail system for example.