[Frank Lee]

I don't draw that conclusion.

As noted, the Tempo wheel has been powdercoated. I don't know how thick, but the paint is definitely much thicker than the other two. Google says typical powdercoat thicknesses range from .005-.030", which:
Bead @ .135" - .01 to .06 (paint both sides) = .129"-.134"
Hub @ .150" - .01 to .06 = .144"-.149"

-vs-

Bead @ .103" thin paint Escort and mini
Hub @ .112" "

OK... still thicker.

Secondly, I don't know if the spacesaver in the Tempo is stock to the Tempo. It probably is but I can't guarantee it.

I've been running Escort rims on the Tempo for many years. If the Escort rim works well, then the spacesaver should too, as far as the gauge of metal used.

Of course the lighter the vehicle the lighter the wheel, generally. I was looking at putting some old-school VW 15" wheels on the Tempo once upon a time and I didn't even have to measure them to know they had quite a bit thinner gauge steel.

I've never seen a pickup with a spacesaver... although it is entirely possible.

I've seen bicycle wheels manufactured... they start with a sheet stock, make a hoop, then spin the hoop through mandrels to make the profile. Because of the geometries of spiders and rims, I think it's likely that they started out as the same gauge material; the rims get worked and stretched more especially at the very edges (where I measured).