Here is the brand I use. It works well and fits between my tandem axles, but the manufacturer specifically allows cutting if the wheels are too close together.
https://www.amazon.com/gp/product/B07PPC57T7/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Note the second piece effectively makes it a chock.
Since you are apparently renting a Class C you will need to deal with some sort of leveling. Most the rentals don't have jacks so that means putting something under one or more of the wheels. I cut some short lengths of 2x6 back when I was renting for that purpose.
If renting from a private party maybe it will come with something, if not then there are devices you can buy relatively inexpensively.
So it's not hidden as a sub-post, I'll repost this here.
Here is the brand of leveler I use (Beech Lane). It works well and fits between my tandem axles, but the manufacturer specifically allows cutting if the wheels are too close together. Also the bag is actually large enough to fit everything back in when you're done.
https://www.amazon.com/gp/product/B07PPC57T7/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1