Had some jungle boots as a kid and they worked fine in the wet. I grew up near a creek bottom and it was wet down there a lot. They do have some leather on 'em and it eventually rotted and cracked after the boots getting wet, then drying out. Lasted me a while, though.
I have a pair of new issue military "for use in mobile units" or some such, not for ground pounders IOW. Friend's boy just got out of OCS and these were some he got somehow and they're my size, friend couldn't wear 'em. They come over the ankle, are gortex/water proof, and as such, have no drain, but they're all synthetics. You'd have to drill holes in the side or something. They really wouldn't be ideal, don't think. Not sure where you'd find any of the old Vietnam era issue, are they still available anywhere?
Another thing about these issue boots my buddy gave me, they aren't the lightest boots on the planet, either.
I've worn 'em ONE day so far since getting them. They're comfy for me, but the weight will get to ya walking much. I will probably just use 'em as motorcycle boots. The water proof part is nice for that.