I had a set of adapters on my old '86 GMC Lwb for about 2 years before I sold it, and the guy who bought it from me still has them on there. That's over 5 years of uniterrupted service. I only had them on the rear to widen the rear track width. And I pulled trailer's all the time...car trailers, boat trailers, etc. Without any issue. Most adapters are made from aluminum, so there is no expected failure issues.
And as far as the offset issue. The Jeep's that are 5x5 are Grand Cherokee's, so the offset on them is VERY positive.
WJ Wheels
All 16x7.0" Wheels: Backspacing = 6.0" Offset = 50.8mm Bolt pattern = 5x5 (5x127mm)
All 17x7.5" Wheels: Backspacing = 6.25" Offset = 50.8mm Bolt pattern = 5x5 (5x127mm)
Where our squares, for instance, use a 15x8" wheel with 4-4.5" of backspacing. So for example, the 16x7" Cherokee wheel would be 1.5-2" further "inboard" than the 15x8" wheel. Pretty big difference
