Can you put a picture up of the glue in the worst area on the boat?
I think your going to need a scraper blade, These ones!
http://www.theladderman.co.uk/module...=11&rangeid=27
I us them alot for alsorts including glue like your talking about.
I removered the painted name of my boat from the area on the hull in the picture to the left here and then polish hull, They made No scratches to the gelcoat.
If you get the angle right the blade should peel and remove the glue.