I have the midnight sun interior - and one thing that I don't like is the way the fabric shifts after repeated sitting in one spot. Quite noticible with the subtle stripes in the upholstery. First I got a rubber brush - primarily great for pet hair - but also puts enough drag on the upholstery to get the fabric moved back where it belongs.
BUT a good upholsterer will always use an underlay between the foam and the upholstery - usually unbleached muslin because it is cheap and strong. The underlayer sticks to the foam, the upholstery moves against the underlayer when you sit on it, but easily goes back into place (or at least mostly) when you get up because of the low friction between the muslin and the back of the upholstery. ALSO the upholstery lasts longer because it's only wearing from the outside and not wearing out from the weave due to friction with the cushion. If you use latex foam (Airstream doesn't on the Safari or CCD trims) this underlayment is especially important.
One of these days when I get around to it, I'll remove my cushion covers and make the underlayment. What's stopping me now??? Well, the last seam has to be sewn shut by hand for a smooth finish. Even though I would use dental floss and a two needle "baseball stitch" it's a chore - because the fit has to be TIGHT.
Waxed Dental Floss makes great thread for sewing on buttons, etc. It is very strong and doesn't tangle. Of course you can wax your own thread with beeswax if you need a color other than basic white.
Today is a gift, that's why they call it the present.