I'm still very new to TTs, and have actually only leveled a few times since buying mine, and did so with some 1x6 blocks I cut. It worked fine, but was a pain getting the right height for leveling. Then a friend turned me on to Anderson levelers. I bought a set and am sold! So easy. Just back onto them and keep going until it's side-to-side level! I am keeping a few 1x6 planks just in case I find that I need more height at certain spots.
https://www.amazon.com/Leveler-Andersen-Minutes-Levelers-Leveling/dp/B01LYQ1Z8S
Check out the video on the Amazon ad.