^ Be sure to use two hose-clamps, push them as far apart as possible along the leg and clamp them tight. It's going to want to twist somewhat oddly and angle upwards a bit when weight is placed on that leg. For fashioning your own adjustable "lazy leg", it may work best to find a section of aluminum or steel tubing/pipe which fits loosely over the existing leg, and use a single hose clamp around the leg itself as an adjustable stop for the pipe. The pipe stays more aligned with the leg since it's slipped over it, and just pushes against the clamp. Loosen and move the clamp up or down the leg to adjust the extension length of the pipe section. Shouldn't need to remove the hose-clamp, just leave it clamped on the leg when the extension isn't needed.
But, I've never had a problem simply finding something to shove under the down-grade leg (usually in combination with jamming the two back legs into the ground a bit), and since that lifts the leg perpendicular to the slope, it needn't be anywhere near as tall as the length an extension will need be long in order to "extend the line of the leg" until it contacts the slope further down-grade at increasingly acute angles as the grade increases. Just need to make sure whatever you shove under there is stiff and stable enough and won't crush down too much.