I have effected a temporary repair with a repair kit for vinyl caravan awnings (that is, vinyl awnings for caravans before mattc or jaded one of the forum pedants pulls me up on it).
It was fine for the first night but I had to add a bit of air for the second. I don't think the adhesive on the patch is suitable for a downmat and I suspect that it will peel off once the mat has been packed away a couple of times.
I'm sure I have a proper downmat repair kit somewhere but, like the loon that I am, I didn't take it touring with me.
<stares sternly over rimless spectacles, for want of a wagging-finger smiley>
And Peli, I was camping with Jane. Lovely as she is, we were very decorous and had separate tents.
</stares sternly etc>