Nothing to make you happy like doing good on a tough job

A brief and specific update on the Gilly sitch: I'm slowly eliminating what Gilly is and is not allowed to play with by noting what she manages to destroy in a matter of minutes and taking it away from her; these items are never bought again. So far, we've managed to eliminate (aside from the obvious delicate shoes and power cables and boxes and dog pillows and Tupperware lids, which she acquires without my permission) any kind of rope toy whatsoever, including the ones wrapped in "durable" materials; soft rubber toys; stuffed toys; and toys with hard plastic components. Which leaves me, in the end, with a medium-sized DuraBone, several made-for-dogs "tennis balls," an interesting-looking woven rubber ball which resembles a ball of yarn (and which is dying a slow death), and a Kong (which Gilly doesn't seem to much care for).

I'm wondering if any of you dog folks out there have toys to recommend, specifically tug-toys, which we can't seem to keep around here. I'd like something that's super(-super!)-tough but won't harm her teeth in a game of tug, and that's the only hardline criterion, although I'd also kind of like something that's dog-friendly on both ends, since I've noticed that the dogs like to play tug together, sometimes, in the brief windows of playtime we get with an undamaged rope tug-toy.

I can look for toys at a store or online, but I've learned the hard way that when a toy is marketed as a toy for aggressive chewers, said toy was likely not designed by anyone who ever met a chewer of Gilly's ilk. Gilly is, like, an Olympic Gold Medalist of chewers. She is a horrifyingly efficient, single-minded chewing machine, my friends. And while I'm kind of secretly proud that she's such a dedicatedly badass chewer, I'd like to find something that'll at least challenge her, you know?