Gelcoated my Mirage seat tub

Not upholstery, but perhaps close enough. I will put cloth seat cushions in (Velcro panels as needed) after I re-install the seat tub.

I Finally got the tub finished out for a final black coat of gelcoat. I modified it in several ways, so that the current iteration has:

1. Passenger seat knee support raised to accommodate the coolant plumbing that runs from the center divider, under the knees, and into/out of the passenger side-pod.
2. Raised and widened the divider to accommodate the 1.5" tubes and insulation that runs to and from the radiator/water pump/engine. This modification also included the raised engine-side tubing entrance that the back-rest sets down on top of.
3. Inserted access panels in each seat for quick access to fuel fittings, wiring, etc that now resides behind the seat tub.
4. Shortened the tub so that it could be pulled back, upward, and out of the frame (done because of the permanently located dash over the front portion of the seat tub.
5. Reinforced the mounting holes with thicker rails to prevent the splitting out that was occurring with the flathead screws.
6. Modified the seat-belt openings so that the tub could be installed/removed without removing the belts.
7. Installed aluminum cladded insulation on the back side and the coolant tunnel portions of the underside.

http://www.fototime.com/C079214417C3427/standard.jpg

http://www.fototime.com/B051D5B747BE3F9/standard.jpg

Lastly, the back-rest (this was also highly modified) was painted a gloss black instead of gelcoat. Seat cushions will be Velcroed into place. The best thing I've found for seat cushion foam is carpet padding. It does not compress near as much as typical cushion foam, and thus is much thinner, and spray adhesive sticks to it very well. After using both, I'll make the rest of the cushions with the carpet padding:

http://www.fototime.com/5FBBB9555493235/standard.jpg

http://www.fototime.com/69BB7BC33ACBC1B/standard.jpg

Looks great! Looks like you've thought of about everything on that one!