Well I am not an expert on either AGM batteries nor your old Parallax 7300 converter unfortunately, but on attached hyper link someone suggests that the old parallax 7300 is not a smart charger and could damage AGM batteries.......but I don't know if those claims are true or who these folks are. But I would re-verify your converter voltages when you are back on shore power and it might be worth considering a modern smart converter that is intended for AGM batteries sooner than later (if the comments are true).
Agm Battery, Parallax 7300 Converter, Cut-Off Switch - Information on the Casita Patriot 13' Travel Trailer - The Casita Club Forums