A lot of people seem to use a WOWA like Optimum Opti-Seal...or maybe I just spend too much time on the Optimum forum. Over there they use Opti-Seal and Hyper Seal. A WOWA seems like an excellent idea for this use, I guess the others still around are Zaino Z-CS...and it seems like the Wolfgang and Blackfire products are gone, although they do have a $50 Wolfgang spray coating, and both have an SiO2 spray product. I think the Ultima WOWA is still around, but I don`t know where you can get it. There is also of course DuraGloss AquaWax, which is kind of designed for this purpose, and always worked well.
Are you planning to use this for conventional or rinseless wash?
I`m sure you will get plenty of other opinions.