Looking in the boats directory, I find China Moon, Eau de vie and Elsewhere with side by side JR (and Grand PHA, Tetis, and an un-named cat with side by side wingsails, which will still give valid guidance on fore and aft mast position). 

I think your best bet, Ernie, is to contact these members (and also Pete Hill, who designed China Moon) directly, by using the "send message" button in their profile, since this is rather a niche subject that not many of us are qualified to speak on, and these folks may not be looking in on this forum. 

All I can say is that I did a little theoretical study with a foil analysis program a while back, and found that so long as the masts were spaced apart by a distance equal to or greater than the width of the sails, there seems to be little unhelpful interaction between the two rigs, and the situation is no worse, and probably better, than that found in an inline, ketch or schooner rig.