I don't claim to know much on this subject however several of the commercial panel prep products appear to have Iso , or something fairly similar as one of the main ingredients. Not sure what ratio of alcohol approaches the danger zone but I am using it at 5:1 so would think I'm good. I've read where some use a 50/50 ratio of iso and distilled water.I tested a bunch of these panel prep products back-to-back with an IPA + water mix the control. The IPA/water does a job, but it has more drawbacks than positives; lack of lubrication, evaporates too quickly to be as effective, higher IPA content in the mix is known to soften clearcoat. If you were dealing with softer paints, then the lack of lubrication could undo the work put into a paint correction. There is the argument that those lubrication elements could work against you, but products like Eraser and Prep have been out for years and I haven't come across information suggesting that they caused problems with the bonding of an LSP. At the end of the day, I do wonder how much money you save mixing IPA solutions compared to just buying a more targeted pre-made solution.
Lack of lubrication is a valid point however earlier in this thread it was suggested to add a smidgen of rinseless to the mix. That sounds good to me. Or even A small amount of soap.
I have been known to be skeptical of some detailing products and their validity. Certainly not all products but with my limited knowledge it appears my skepticism may not be far off the mark concerning panel prep products.