I can't really offer much here, given the huge differences in how our aloes grow (the greenhouse, the months without water) ... just some thoughts about treatment. Peroxide is toxic to plants at a sufficiently high dose, so if you go that route (as with any chemical treatment) be sure to measure and use the product in moderation. Alcohol (I use 70%) is tolerated very well by aloes above ground, but I doubt that is the case for the roots. At some point once you spray enough on the leaves, you will begin to treat the roots. So again apply in moderation, to avoid adverse consequences. Not sure either treatment will do much good, but at least you can avoid them doing actual harm.
When one of my plants loses its roots to rot, I tend to shrug and toss it without investigating further. So I really have very little idea what kind of organism is involved, often I am clueless about what the inciting event might be. Except that it tends to be associated with (1) too much water (at one time or over time), (2) roots being weak to start with, and/or (3) the pot having too much soil for the size the roots (probably through mechanism #1 above).
Also worth noting that root loss to rot may also be related to insufficient water over the long term. This perverse mechanism seems to be related to some kind of chronic weakening of the roots (see mechanism 2 above) which leads to a rapid collapse when they are finally watered properly. So it's not so much the watering but the insufficient watering preceding it that makes things go south. Probably not the issue for you Steve, just including it here for the sake of completion. Especially not relevant in the face of this upcoming drought which you apply during winter, which is very different from withholding water during active growth, and which has worked very well for you in the past.
Weird to be typing without my left index finger, so I will stop soon. I lopped off the tip of my finger yesterday with scissors as I was trying to take a Dudleya cutting. The Dudleya cutting will likely survive but the human cutting was lost somewhere inside the mother plant. Much blood, so much blood, the dog was very interested in my bloody bandage in the aftermath.
