I agree offset is not to be used as a measure of clearance inboard. Even backspacing alone isn't enough because of the need to factor in sidewall bulge which is largely dependent on the tire (e.g. the 275 will bulge ~10mm more each side than the 255 if the rim is the same).
I've been trying to be more mindful of maintaining an offset close to the stock 12mm (most rims I've been seriously considering are in the 0-24mm range) in order to avoid introducing steering issues and excessive front suspension component wear. The latter is more of a concern when running towards the negative offset direction as I understand it.
The challenge is that most of the rims I like are all further offset in the positive direction (24-40mm) which is where the clearance issues arise hence the need for spacers. You bring up good points about the longer studs, Don. I'm RWD, so I'm less concerned about damaging a front hub when installing studs but after thinking about the mechanics at play, the longer studs will certainly be more prone to deflecting during a launch -- and breaking off a rear wheel at speed doesn't sound fun.
To clarify, Don, the most "aggressive" setup you've run was a 265 tire on an 18x8.5 at effectively a 28.65mm offset? And being lowered ~2.5" in the front your only issue was the tall 60 ratio tire rubbing the inner fender? That's pretty impressive to me, I'd expect way more rubbing with that large of an offset and a 265 tire.
If I'm thinking about it right, your effective rim backspacing would have been about 5.88" [(8.5"+1")/2+28.65mm] and the tires would have been inboard from the hub 6.84" [(265mm+1")/2+28.65mm]. With a 275 tire on a 9" rim with +24 offset, rim backspacing would be 5.94" and inner sidewall would be roughly 6.85" from the hub. I can't say the 17" rim won't have other clearance issues, but it looks to me that if your setup cleared, the 275/55R17+24 should too.