I successfully stripped lexan sheels (both 20r old paint and recent stuff) with an auto valeting product called Autosmart Tardis - you can buy it on eBay. It smells remarkably like Tamiyas own lexan cleaner, but its about 1/20th the price. Some paints it seem to almost dissolve on contact, other take a lot longer.
I soak a cotton rag , lay it on the shell for a few minutes and then rub away at the paint. I've cleaned an Avante shell in under 10 minutes, but a Durga shell took several hours on and off, and a vintage Egress shell, brush painted with various paints took a long time.
It works, doesn;t fog or micro craze the lexan and can be repainted without issue.
Original Avante 58072 shell, stripped of paint in 2012..
Original Egress 58079 shell, before..(yes that is hammerite on the undercowl!)
during..
repainted..
Original 58100 Top Force, on arrival..
after stripping and repainting..
