Hey Cartographers!

I'm trying to build a map with hand-drawn map elements, reused over and over again at small scales. Partially inspired by Darklingrisen's tutorial, and Ironmetal's as well.

Darkling's tutorial utilizes tools in GIMP that photoshop lacks (brushes that contain white and black, instead of converting white to transparency, brushes that randomly choose between different shapes), and Ironmetal's is about how to draw the shapes, not use them.

The biggest problem I'm running into is how to quickly apply elements like mountains. I have 8 or 9 mountain elements drawn. I want to be able to quickly place them, with some random variance in size. Photoshop can handle that much with the jitter settings on a brush. I also want to be able to place mountains so that they overlap a bit - the problem here is that "white" on a photoshop brush automatically becomes transparent, so if I try to place two overlapping elements, they are both visible. Going back through and hand-fixing the overlap would be incredibly time consuming. Finally, I'd love to be able to quickly and efficiently switch back and forth between different mountain brushes. Right now I need to select a new brush each time, which isn't the end of the world, but it's not ideal, either.

So how do you guys handle this sort of workflow? There are definitely artists here who seem to have sorted out some or all of these problems, and I imagine that some of them even used PS to do it! Examples:
Imperial Worldmap of Arden by Schwarzkreuz
The Butcher, The Baker, and that Other Guy by Ascension
The Lands of Todes Grube

Thanks in advance! (Even if the answer is "stop complaining and eat the time-consuming clean-up work!", hah)