I'd personally worry about wearing a wig that had basically been dunked in fabric softener for any length of time...that's a lot of chemicals that could leech into your skin. Personally, I prefer doing the acrylic ink+isopropyl alcohol route. Even if I have to do it outside so it'll be well ventilated, once the wig is dry and has been given a rinse there are no lingering chemicals.
Although it may not be as precise as your method, especially for things with multiple colours/stripes in the wig. It's good to see that there's another wig dying option out there though! The more options the better, but I think I'll stick to my usual method for now.
That's true, but I used it since people already use the fabric softener to condition their wigs, so I suppose it doesn't bother skin too much. Thank you for pointing this out though, I do see where you're coming from.