Just my 2 cents.
I've never see a mutoh rip that allows for multiple strike printing. Now if you set it to high quality you may get a 16 pass print... but you need to have a color profile setup for that. Its not like you can just play around with the print modes and expect consistent output.
Regardless of what people may say around here print modes are directly tied to the color profile. So if a profile says its a 720X720 CMYKLcLm High Bi Directional High Quality....then just picking 1440X1440 as your resolution will not get you correct output.
Pretty much, 4 color process ink jets don't print very good on clear because their inks are transparent. You'll always need a white underbase. To print a back light
sign and have proper ink density when lit, here is a trade secret. Print the front of the
sign on translucent white, then reverse print on clear and mount that on the back face of the
sign. This gives you a double density print. (and yeah, its just as much a pain as it sounds but at least your customer isn't having your replace a
sign that looks faded when lit)