I don't think that there is anything peculiar about the Ford Ranger that would prevent it from working.
I was the one who recommended the dowels, and they work fine for me on my Chevy Astrovan. The dowels do prevent permanent seal deformation.
The window goes up and down without any problem.
Is it going to let some rain into the door? Probably a small amount, but your car should have some way for the water to drain out the bottom of the door even when you don't use the mirrors.
http://www.hensleymfg.com/xcart/customer/home.php This is the manufacturer from what the website implies and I would recommend going directly with them in case there is a problem. Easier to deal with them, though I didn't have a problem. Ask about the $119 promotional deal. I would be surprised if you could save much more than that. They are worth every penny in my opinion.
Bob W.