Over on the LF forum someone came up with a good design for a barn door adjustable hood. Such a thing doesn't mask the corners, but you can adjust each door independently and rotate it against direct stray light, so it should work pretty well. I have a Voss clip on hood that I use with some lenses for which I don't have another good shade/filter option. It only has two doors, so not as good as four, but it takes 3" gels and is better than no hood at all.
Yet another adjustable option is a 3-position rubber hood, which isn't as precise as a compendium shade, but is convenient for traveling light.
Out of curiosity - the compendium hoods sold by Shen Hao, Toyo etc, anyone have any specs on those - in particular how large is the opening that fits over the lens. I'm wondering if there is anything out there big enough to fit over the Schneider XLs with center filters attached (112mm).
I spoke to someone at Lee who indicated they have a nifty slip-on attachment specifically to fit their wide angle compendium hood on to the Schneider 90/72 XLs. I like that idea. It's fairly simple. The limtation is it only works with those lenses without the gigantic center filters on. They don't make a hood large enough to fit over those 112mm center filters. Still better than nothing though.
Compendium hoods for 4x5" cameras are often 4" square, so they can hold 4" or 100mm square filters.
I picked up a Toyo View conpendium hood relatively inexpensively at a camera show. Overall dimensions of the frame for it are about 155mm square (just over 6x6") with an opening of about 125mm square (5x5"). That should handle the filter sizes you are talking about.
I am looking at using the front to mount the 8x10 or 8x20 format mask, and a seond mask on the frame nearest the lens with a circular opening to handle filters in a Calumet Xenphon filter holder for either 4x4 or 3x3 rectangular filters. Both masks looking at using velcro to mount the masks and be able to repostion them.
The funky issue is fitting them onto two very different and old wood cameras without modifying the cameras themselves...
More for you to ponder,
Ever tried a gooseneck clamped to you camera and a scrim attached on it?
In the film industry, this was usual as an alternative or complementary to the matte box. BTW a matte box might work for you too, there are a variety of sizes and adaptors for different lenses and situations!
An other way, particularly for optical bench camera's, is a second bellows with two stands (can be found used), mounted on the base rail, in front of the lens. This way you can move these bellows accordingly to the lens movements, that's what Sinar (Norma) propagated at the time.
Linhof has a compendium that can be attached in the accessory shoe. This is the one I have for my Linhof, light, flexible and adaptable.
Below, in the first picture you can see it on the right and in front the filter holder, in the last picture you see the attachment that fits in the accessory shoe (upper left) but here the compendium has been modified a little. How it coms in its simplicity, you can see that in the second picture.