I make "gillie-mocs" very similar to these. I wonder if a high-top version, either with good, heavy leather or with a stiffer rubber sole glued or sewn on, would give adequate support? They're quite easy to make: I can make a pair of these in about half an hour with a good pair of scissors, a rotary leather punch, some artificial sinew, and a heavy sewing needle (and I'm a huge clutz). They are also really easy to customize so they fit, so you would experiment.
https ://www.youtube.com/watch?v=Z13qgcksoU4&t=215s (remove space after https)