Dog With Hip Dysplasia: Shopping For A Ramp

DARRYLDAWKINS asks: "I have a 10 year old chocolate lab who is showing signs of hip dysplasia. He has a lot of trouble getting in and out of our RV when we go camping. I've been looking online at ramps and have found a few that might help out. I'm wondering if anybody has experience using these ramps and could provide a suggestion for a make or model, as well as any other considerations I should be making."