I looked at adding a step and found that is was not worth the cost so is now use the following:
Folding Aluminum Platform Step
Manufacturer
Stromberg Carlson Products Inc Mfg Part #: PA-100
Description
Wide base design and unique double-locking safety legs make this step one of the safest on the market. Gripper strips on roomy platform and non-slip leg tips ensure that your feet stay firmly planted on the step.
Construction
Lightweight, all-aluminum provides up to 1000 lbs. of support.
Legs lock in 2 positions for 3" or 8" step height.
Platform measures 19" x 14". Folds to only 2 3/4" thick.
Silver powder-coat finish resists corrosion.
Technical Specs
Tech Specs
Weight: 7.4 lbs.
Step Supports 1,000 lbs