Unfortunate as I mentioned, with Y, which I've done for years, is just a mess of tight walls, and you have to mix in colour adjust cascading surface layers at different alt restrictions if you want it to be domed correctly. It also doesn't rid the noise completely of artifacts floating alone above 0.
A 2D map would be ideal for flat bottoms clouds. In fact, clouds are so easy to construct in UE and stuff because they're just rasterized maps used as the scalar and location masking, and are easy to construct realistic clouds without all the spoofing you haven to do in TG.
0 is the bottom of the cloud range, 1 is the top of the cloud range. So all soft noise should cascade inwards to form domey-like tops to clouds, no extra noise floating above it continuing on Y forever, just what you see is what you get. You get perfect flat bottom clouds with cumulus tops. All you need to do is taper bottom of clouds, or use a surface layer, and pretty much they're based on just the density and that surface layer, no extra work. Thnk of a simple shape shader at 100%. It's 2D. It creates a flat bottomed dome.
And let's be frank. I still have yet to see realistic cumulus clouds without them being luck of seeds, or obscured in some way to hide all the bad bits, or constructed so elaborately no one dares share.