It's hard to tell from the proto photos, but do the trousers have a military style hem at the bottom? A military hem is higher up the leg than a regular one so that the hem doesn't constantly rub on the boots and cause it to fail. The ones used on Indy's ROTLA trousers seems to have been about 4 or 5 inches from the bottom. Top pic is from Raiders, bottom from Last Crusade but since it's clearer I'll include it here.
View attachment 189717
View attachment 189718
I haven't seen this done on any 1/6th Indy trousers to date.