Unhitching safely on deep grass - slight slope

^Then it's not a "slight slope".
All the "gadgets" they sell for chocking wheels if one notices, are aimed squarely at the RV market. The other 90% of trailers on the road use either simple rubber chocks or lumber, bricks or rocks, etc.
It's akin to the wdh and sway control marketing. Sure some tow rigs and some trailers need help either due to payload capacity or the particular trailer loading, however they get sold as a "must have" and RV ers gobbled them up!