as stated earlier, TB rims have a 6" backspacing, not sure what a Tahoe or other OEM truck rim back spacing is, but here are a couple of ref. pics. on how far they don't stick out.
markmc's 1-5" spacers w/ 265/70/17 on TB oem rims.
I would be concerned too with a 4WD. but if I had to replace hub bearings on a 2WD, should really be easy. But the guys with lifted trucks and spacers or adapters would have to chime in if they JUST do trail runs or if its a daily driver
Its been stated many times over the years that the additional stress is really minimal and nothing can actually be proven as the spacers being the culprit. They are no different than using aftermarket wheels typically and no one even blinks about those causing extra stress and wear.
Most that say that the spacer/adapter are causing issues also have lift and heavier tires and/or wheels. Plus many go to spacer/adapter when lifting which inherently shifts the wear patterns of many components and can lead to failures if any of those parts are not new when lifting.
2wd and 4x4 hubs are the same so no need for concern.