(UTC)
You got it right in your second paragraph and then erred in the last. It's not a noun but a contraction of an implied "... than 10 items". — LlywelynII 
Your gloss makes sense but you're fixing a non-problem. "Less" has been correct since Old English and only becomes. The proper solution is to ignore them, not contort yourself. The posh who would object in the first place won't be impressed by your linguistic gymnastics; they'd simply mark you among the hoi polloi who don't speak as they do and move on with their day. — LlywelynII 14:38, 26 January 2014