You could get clever and build the dorades out of acrylic
While a cool idea, may not be aesthetically pleasing in practice. The inside of a dorade box can be quite dirty and often has something green growing.
With respect to the location, we have a similar issue and our sheets were always catching. I considered making guards but one day simply turned the cowls aft and the sheets haven't caught for 4 years. They simply slide over the top. For this application, I'd recommend low profile cowls and not the large stand up ones. We used SS ABI cowls as in this link:
SailBoatStuff - ABI Low Profile Cowl Vents, Compact Cowl Vents, Round Cowl Vents and Parts