Hi Sherryl,
I have a longarm (Gammill Statler) and I use and have customers use Minkee on the back all the time. The trick to using it is to not stretch, or pull taught like you would with a cotton back. What I do is load the minkee on the regular way but then when I start to roll it up then I stop once it is flat and not pulled. Then I do the batting and then the top. Some of my customers don't even use batting and I have one customer that once she found out that I can do minkee.... she has never used a cotton backing since.
The trick if you even want to call it that is not to pull it.
I have even done minkee on the top with minkee on the back, that works the same way.
Rose