I did for years keep tight track of what I had, sold, and wanted, even with some notes and margins (mostly lack there of) to keep myself in check on the taxes end. All in excel, then it got out of hand of the rate in/out (almost all pedals) and I got behind. I need to update it, but more than anything, I have it incase of a total house loss so there isn't as much of a fight to get the right funds for stuff lost. Weird, I know.
Oddly, playing music and getting back into skateboarding has been kicking my ass and free time.
What @davedamage said, the hpf (even those cheap ones) will help protect a ton. Thats actually part of the reason I trend toward sealed cabs too. I like the punch more from them, and dialing in an hpf on a ported cab helps, but i like the added security of a sealed cab. It dampens cone excursion down low a bit, and increases the lower it goes (hence the tightness) vs once you go below the port frequency you run the risk of uncontrolled cone movement on ported.
I dont know a ton about it, but aged horse does of course, as others do too. I just know that once I started pushing some dirt and/or envelope filters with an octaver that occasionally I would start causing some oddness and farting on my mesa 2x12 powerhouse that could handle way more wattage than my amp could push. That was the last thing I wanted to blow a speaker on.
An hpf helped, then I realized that with enough db's, sealed cabs can cover enough lows no prob. A la the fridge, so I snagged an old ampeg v4 cab and put some bass speakers in there. Tons of punch, air movement, and more than enough lows for me. I still use an hpf just to make sure too much unusable lows go through but haven't had a problem since.
I recently rechecked, just to see if there was any user bias and with a 610hlf, mostly same results. Definitely dont have the science down, but with how heavy handed I play, it's good to know I should be okay.
BTW, I almost always avoid 2 octave down.