It does help.
I can't find my books again (or my modelling knives at home, really annoying) but I think in the SoTR background Spain joins with Germany sometime before D-Day. Italy still loses out, unfortunately, because I feel they could be an interesting force.
As the Spanish uniform was quite similar to the German one I don't think there's any need to paint them up as Heer. It's certainly a small enough difference with an obscure enough force that I can ignore my disturbing increasingly rivet-countery tendancies.
I had forgotten all about the Gewehr 43. I did wonder why I didn't think of it as an option, but I realised why when I checked the Assault Group weapons list again, this time specifically for it, that they don't make one. Is there any company that makes G43s? Unfortunately the Westwind German weapon packs have 3 rifles to a pack of 15 weapons. I'm basing my squad load outs around the American ones (there's no Spanish OOB) so that's a pretty unworkable mix. Also, they are pretty high tech, I'd prefer the Spanish to have earlier weapons.