I had this discussion with Greg C last week.
He says that any 'rifle' type recoil pad (NOT the large, curved, trestle-type shotgun pads) will be accepted at nationals provided it is properly shaped so that it follows the contours of the original stock lines.
If you show up with a pad that is just 'attached' (not shaped to conform) and it makes the butt area significantly larger, deeper, wider or higher than the original (taking into account the expected, small change due to the longer LOP stock) you will be in violation.
The original intent of the committee -- according to GC -- was to allow a thin rifle pad of the type found on many guns from the factory (because, since shooting vests, jackets and such are proscribed, there's no provision for a non-slip clothing surface) but that's been 'expanded' in order to cover people needing longer stocks...and because it's recognized that many used rifles will already have pads installed when purchased.
I like cowboy. Not as much as I enjoy smallbore rifle, high power rifle and air rifle silhouette, but it's a lot of fun and (because it's easier and -- until we start letting the equipment-race types get their way-- cheaper?) it's attracting new shooters. That's always good.
I do, however, see it as creating a problem for people (I'm one) who think that there should be a dividing line between competition 'tools' and original rifles that have achieved collector status. IOW, I dislike seeing someone buy a nice, original old Winchester or Marlin and start drilling sight base holes in it or sawing on the stock in order to chase some -- often-imaginary -- advantage on the line. OTOH, I think cowboy lever is saving a number of old rifles from rusting away in closets. I guess we take the good with the bad...