Stabilized with the ground.....
Found an exercise workout step, which is about 4" high, and much *longer/wider* than the trailer steps. Hard plastic - has short add-on legs for each corner which would make it about 6-8" high (Still very stable, but I never used those).
Just set it on the ground under the bottom step.
Check Wally or a sporting goods store.
Or - you could simply make your own (wood).
The Redi-step is fair - but 4-step folding permanent, (replacement for 3-step) are available from RV suppliers (and via Amazon) - for about $200.
There's also an inexpensive "stabilizer" which can be placed under a/the bottom step to stop flexing. Check RV suppliers.
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