Barbara, if you don't fancy a boring Burgundy or Green,you could always opt for an equally boring Blue or Silver/Grey.
There is not really a market for these covers, as the only benefit they have is the fact that they hide your make of Hitchlock and protects the Electric sockets and other components from the weather. Ours is Burgundy, the same colour as the Aquaroll and Wastemaster bags, it also blends well with the colour of the Awning (Burgundy).
I do agree with you not wanting to freely advertise the Dealer, but unless you are willing to make one yourself, then I am afraid you don't have many options,
best regards, Martin