Jesus, what a tough puzzle! If only we had remembered Huygens' explanation of MRE (61D: Post-hurricane handout, for short), we wouldn't have been groping for so long in the SW. PENROSE (63A: Mathematical physicist Roger)? And who knew that Natty BUMPPO (45D: "Leatherstocking Tales" hero) had two Ps? And then there was the middle. How we stared at the middle. Frannie suggested DRIB or "drab" early on, but I resisted. Finally, near wit's end, I put DRIB (39D: Smidgen) in, and then, finally, with that final I, I was able to see JIMI (47A: "____ Plays Monterey" (posthumous 1986 album)), which gave us the end of BALLTHEJACK (18D: Go for broke). What the? "Ball the Jack?" Has anyone ever heard that before?? I looked it up just now, and the Urban Dictionary definition is "From the '30s, means going really fast, mainly with a car or any vehicle." The examples they give are: "You can really ball the jack in Germany" and "I was late, so I balled the jack on my way downtown." Now I love the expression. I will be using it all the time from now on.
Where was I? Oh yeah... does anyone know BETTYS (23A: "____ Bein' Bad" (Sawyer Brown country hit))? After that Ball the Jack experience, I'm a little afraid to look it up. I might get a new favorite song out of it.
Anywho, there was a lot that was good in here, it just sometimes took us forever to see. Like TKO (40A: Swinging halter, for short). I had put in VaN for 36D: Part of many a German name, and had ended up with TKa, which didn't make any sense, but I still couldn't get it. Frannie, luckily, said "Van is more Dutch, I think this should be VON, and finally, TKO was all spelled out, and only then could I see it was a boxing reference. Wow. COMEDUE (1D: Mature) took a while, CAROUSE (43D: Whoop it up), same. A lot of the long ones fell fairly easily, like LIFEISVERYSHORT (12D: Why "there's no time for fussing and fighting," per a Beatles hit), but they didn't help with the middle. Even when we had OVERTHEEDGE (37A: Flipped out), we still couldn't get things like YETI (34D: Humanoid cryptid) or SEEM (35D: Feel) (this, to me, seems like a slight stretch).
So I could go on and on, but perhaps that's enough. Wait, just one more - ANAGRAM (2D: Antes up for peanuts?) BRILLIANT! Ok, that's really it. This was a nice challenge after last Friday's cakewalk, but at the end we were just grasping at straws. Technically, a DNF, but we did finish unassisted after getting the error message a few times. Now I'm gonna go ball the jack to the packy and try to forget all about it.