Spinning lug nut.....how can this be possible?

Get a Dremel cutoff wheel and cut 2 channels up the side of the nut cover so you can peel the cover off. Do you have a standard nut then showing (metric or standard) left? I've never seen a lug covered with sheet goods that didn't require the cover to be removed before the lug was loosened.
You need to specify what the lug (flat) was on. RV? Make, model, year, Toad? Same, make, model, etc.
RV lugs with decorative covers usually use something like these Cover pullers
to remove the cover.