Now that you mention it, it's not necessarily out of a question for LMP3 to have that support race this year already. After all LMPC (even acknowledging that it was series of it's own at the time) got it's LM slot for debut year when the European grids were still alright
http://www.racingsportscars.com/resu...09-06-14f.html
I think "LMP3 Le Mans Cup" would be good way to attract new customers. Then fill up rest of the grid with CN cars, Lites, old PCs, Radicals, vdev-stuff and whatever to avoid a sight of ten cars rolling Mulsanne alone.
But well even if/when not, P3s can run at Test Day at least.