You can see if RT uses camconst data for your cameras by looking in console (set verbose=true in your options file).
I read in console that RT is not using D800E data for D800. For this to happen, all you have to change is the "make_model" line to
"make_model": [ "Nikon D800", "Nikon D800E" ],
Is it hard if I ask for a full set of white samples ?
Ingo, this is how Dcraw works sometimes but not camconst (and I think it's better this way..)