William Duffield
don't have to stoop over as much

You wouldn't have to stoop over at all if, instead of clamping it to the top of your bench, you bolted it to the front of one of these metabenches…

…using hardware like this (or BenchCrafted's kit):

Make it any height that feels comfortable. If you make it too tall, just cut a bit off the bottoms of the legs. I prefer to be able to just rest my elbows on the top of the bench when standing upright with my arms resting. Another savings is you only need one jaw. The front of the metabench and whatever you clamp that to serves at the rear jaw of the Moxon vise.