rc51, gvjay, and bobinsd - thanks for your responses.
So the baling is done, the baler is unhooked (quite a chore), and I'm trying to get a solution now, while things are still fresh in what's left of my mind.
I have two approaches I'm focused on:
1 - Make longer bottom "pins" for the implement. The photo below shows my cheap steel mockup, which bent almost immediately (the green duct tape was my mock bushing). I've ordered grade 8, 8" x 3/4" bolts to see if I can make longer pins that are strong enough. If so, this effectively widens the width of the baler, so it'll fit on the QH15.
2 - Return my QH15 and get a set of the "Pat's QH". If I go this route, then I also want to effectively lengthen the toplink holders that are bolted to the tractor (by 3" or 4"). So I'm wondering if "longer" (from front to back) toplink holders are available? It appears that the "Pat's QH" would let me adjust the distance between the two bottom links easily for each implement, as opposed to having to make all the implements exactly fit the QH15.