OK heres what I did. I made a manikin based on V2 and a full body morph to make it into V3. Difficult but not frightfully diffcult. This is not a posable character but a chater with only one body part. But so what! Tailor still accepts it as a regular figure. As yo can the catsuit fits perfectly. Yes you read it coreectly the catsuit!!!!! You know th e one thats so tight that barely fits V2 who its desinged for?
One I got the V3 morph on it, I just applied FyreSprytes V3 Joint parameters pose file at
http://www.shininghalf.com/desprit/downloads/V2clothesToV3.zip.
Just one problem- since V3 only has one neck part you have finagle teh Cr2 to get the upper neck to conform to eth head. You have to change all occuarnces of "upperneck" to "head" except for the one beginig with "geomHandlerGeom 13" the But since few clothing have parts for teh upper neck it shoudl be OK.
I found these worked fine without having to regoup