Create multiple masks for a layer?

This would really help me. Right now I add multiple layer masks by nesting them in folders. Smart objects are the only other option, but I wouldn't be able to see how they all interact while I'm editing one that's nested in. 

My use case is making things look aged and hand-painted. I link my vector artwork, then mask it with a bristle brush to make the edges look painted and uneven. Then I mask that with a painted BG texture so the fill areas are uneven. Then I mask that with the texture of the background behind it, to make it look like there's no paint where the background is flaking off or where timber planks meet.

I need multiple masks, otherwise if I wanted to change the background texture, or the paint texture, or the painted edges - I'd have to start over from scratch every time. It's really helpful to keep them all separate.

I found this thread after Googling, "Can I apply multiple masks to a layer in Photoshop". So I'm weighing in very late, but it would be helpful to me. 

The thing I'm trying to do right now is apply a feathered mask to a layer, but then do a hard mask that lines up with elements below the masked layer. I know I could group the layer and add a mask to the group. The thing is, this layer is clipped to an underlying layer, so it can't be grouped. 

The suggestion to make the layer a smart layer and copy/paste a merged copy of the other layers for reference sounds great, and is the way I'll go in this case, but it would be a lot cleaner and simpler to have multiple masks. Also, the ability to control the opacity of those masks would also be helpful. 

Two more use case scenarios where this would be helpful in my workflow.

-being able to adjust the strength of the masks independently.

-when exposure blending a landscape image, I tend to use either a gradient or a brush on the mask.  It would be nice to be able to to have multiple masks so I could apply a gradient to one and then follow up with some brush work on another.  Being able to turn either mask on and off to see the progress would helpful, and adjusting the strength of each mask independently would be helpful.

Cheers!

I saw this post last night and decided to really think about it before weighing in.  @Chuck Uebeles comment really got me thinking about the idea of subtracting from the first mask or primary mask, and the idea of adding a luminosity mask to either add to or subtract from the primary layer is appealing.

So for instance using a levels or curves adjustment layer on some clouds.  I could mask the clouds without being too precise, and then apply a luminosity mask to target light or dark tones.  I already do this with a 50% grey layer with a luminosity mask applied, but it's not adjustable like a curves or levels layer would be.

This has potential to really save some time and open up new uses for adjustment layers.

Skill level is moderate to advanced

It's doable now by using nest Smart Objects.  

You add a layer mask to your layer, and mask the required area.

Make the layer a Smart Object which incoperates the mask so you can add another.

To edit the original mask you have to double click to open the SO in another window.  That can be problematic in that you can't see the background you are trying to mask, but that is easily fixed by Duplicating the background, or a copy merged layer of the entire background, to your SO window.  Edit the mask as required, and turn off the copied background layer before saving the SO.

You could the same thing using nested groups, and that has the benefit of  being able to work in the primary document window.

I think the reaality is that might well be better workflows that negate the need to use multiple masks, like clipping mask layers.  My default method for warping an object to fit an exact space is to select that space and fill the selection with black on a new layer. I call that a template layer.  Then clip the warped object to that black template layer.  being sure to get a tiny bit of overlap.

Just offhand, I would say this could be a good thing. For me, it would be being able to create a complicated mask then add another mask to modify it without destroying the original mask. So what it would need is the ability to add or subtract from the primary mask, much like masks in ACR.

There is probably other advantages, but that one is something that I've wanted for a bit.

Skill level is advanced.