I had to install handholds for my wife in our fifth wheel.
She has difficulty climbing the steps, after her hip replacement, to the bedroom from the dining/living area, using the toilet and getting in and out of bed.
I carefully pulled the Luan paneling away from the "studs" in the wall.
These "studs" are 1 x 3 pine cut down to about 2-3/8" width.
I added 2 additional pieces at each of the three locations and glued to the existing framing, and replaced the paneling.
Plenty of strength for the handholds. I purchased mine from Home Depot.
This took care of the interior.
For the steps I purchased a product called "Glow-Guide Handrail", http://www.torklift.com/products/glowguide.php#a7610.
Simple in install and remove for traveling.
Hope this will help.