Steve we strive to help. Nice looking web site.
If i were going to do the white on a seat, and you being a painter.
In the U S , at the shoe repair shops there is a Paint that comes in an aresol spray can
Meltonian...Nu-Life ColorSpray..
The again you might want to experiment with some Lacuqor Paint.
Now be prepared to do a lot of masking with tape.
this would be a better white than the acrylic......hope this helps you.