Why not wear waterproof socks under your leather or otherwise boots, sealskins for example, and wear wet suit bottoms (underneath waterproof trousers, to protect them from wear) or a full wetsuit. Or a breathable dry-suit, or dry-suit bottoms.
SInce nobody is watching, can't you just strip down, pass, dry yourself and get clothed again. Clothes go in a watertight pack when crossing. Some surf-shoes or similar so you don't hurt your feet when passing. I got one of those lightweight towels and they are excellent, dries really fast too.
If I could buy buffalo pertex in a size 56 chest I'd buy it but I can't! But yes it does seem ideal. I wear piled fleece in the winter and it retains a lot of warmth when wet but it is not as good as proper buffalo pile.
Sealskin socks are rather short don't you think, not to mention cutting off your blood supply to your calfs!
Have you tried walking in a wetsuit? Obvioulsy not for any distance... Let me nkow how you get on after a couple of clicks.
A full dry suit, well again a good idea but it would need to have all the vents for ventilation like the latest mil ones otherwise you'd overheat. But yeagh for the really rough stuff an affordable dry suit would be good. Once I slim down a bit that'll be an option.
Just a suggestion, I've never used them so don't know whether they are short or cut off the blood supply to your calfs.
No never worn a wet suit, no idea how good or bad it would be, just a different suggestion, your the one worrying about getting your troosers wet!
What about just the wet suit bottoms?
Or alternativley what about longjons underneath waterproof trousers. Longjons would dry quicker than trousers, hold less water when wet and still provide some insulation. Worn under water proof trousers they shouldn't get too wet anyway.
Coupled with decent gaiters your lower half shouldn't get too wet in a short wade.
As suggested above take your socks of and put your boots back on to wade then you'll have dry socks to put on, and to keep them dry you could always put your feet into polythene bags before putting the wet boots on.
Long story, but the gist is that my Father lived wild on Rannoch Moor for three years before the war while he recovered from Rheumatic Fever.
He said that long shorts and bare feet became an incredibly practical way to live, except when the ground froze or was covered in snow.