I used a 'green'
paint stripper (on hull stripes) some time ago, it was effective despite cooler than optimum temps at the time... but while it was clearly advertised 'safe for gelcoat' it did contain a warning to limit the application time for epoxies.. This was called 'Aqua Strip' but it would be worthwhile to check for sure that the stripper they are intending to use is
epoxy-safe.