I think you’re right. When it’s unremittingly soaking wet, rubber boots are unbeatable. I was on an August trip to Alaska’s southeast coast, and it either rained or was about to start raining the whole time. We wore rubber boots for all our shoreline excursions.
The downside is that rubber boots are not fantastic footwear, from a comfort, support, or grip perspective. Finding a pair that can stand up to those tasks is difficult. I have in my gardening arsenal a pair of rubber Wellingtons from Smith & Hawken ($62). I’ve retrofitted them with Superfeet insoles ($28) for better stability and arch support. They’re well-made boots and work pretty well for extended use, although I must say I haven’t trekked in the jungle with them.
It appears the place to go for really serious “Wellies” is the United Kingdom, where they originated. There, a company called Le Chameau makes Wellies with Vibram soles. The model you’d want, I think, is the Vega, which sells for about $150. The challenge will be finding a pair in the United States. But, you might visit one of the Vega’s online UK dealers and see what you can work out. Try .Happy hiking!