The only issue is that there isn't a template for the thicker ass and legs mod that I can open (afaik). I can insert an image of the taal onto the basic template and use that as a template of sorts. However I reckon there will still be a bit of work re-aligning and resizing the markings properly for whomever may actually implement the SWF.
ffdec allows you to decompile SWF files into their assets. You can export the pieces of the thick thighs mod as SVG files. Of course you can ignore the arms, chest, etc.. since those bodyparts aren't changed by the Thick Thighs mod.
You can copy-paste the new legs into the body template and draw spots on top. You could decompile the Cow mod as well, copy-paste the spots into place on the template (so you have "skinny legs", "skinny spots", and "thick legs" on the same canvas) and then stretch or extend the original spots to fit. Or you could just draw an entirely new set of spots.
The key idea is that you'll be drawing multiple sprites (right thigh, left thigh) each with its own set of spots. This work must be done using separate layers. You can't just draw a single-layer image which shows a set of spots fitted onto a snapshot of a kneeling girl. You need to draw a full set of spots for the left thigh, including the region which is normally occulted by the right thigh.
If you'd like to draw spots for the calves then feel free to do so -- I'm not sure why the original mod excluded them.
If you'd like to draw spots for the breasts then we'll need to discuss it further, because there are some complications involved. The easiest approach involves masks, but that usually means abandoning vanilla compatibility and publishing a Loader mod instead.
If you'd like to see any changes to the mod then be sure to mention them. The cow "hairstyle" in the original file seems to be disabled; we could restore it. The tail could potentially be omitted if you're looking for a "bodypaint" or "cosplay" effect instead of "monstergirl".
