Portable Steps for Older Arthritic Dogs?

My big dogs are getting older and are having trouble getting into my
truck. I saw an ad in the Dog Fancy magazine for something called the
petloader (www.petloader.com) and wondered if anyone had any experience
with it? It's somewhat similar to the twistep (www.twistep.com) which
looked like it might also have potential. I have a ramp but neither of
my boys will use it and it's kind of big to lug around. Any insight is
welcome.

Thanks
Cathy