Another possibility might be the new MorRyde "StepAbove" entry steps.
It would seem you could add outdoor carpet to the treads, and make
your own "add-on" full length side rail to make the dog/s feel secure.
(The optional hand rail would benefit you - but not the dog/s).
Also there is another mfgr of entry decks, which break down for storage but not quite as "user friendly" as Port-A-Deck - but appear to be of sturdier construction.
Try a google search(?).
(I'll come back with the name if I find it)
:C