Your idea of using 2 lb. test line is probably wise but trying to predict how a fish will make the first move is difficult. I suggest you test your idea by connecting the two pound line to the boat and attach a three pound rock about 4 ' downline and drop the rock while the boat is sitting in the water. If the line breaks before the boat, you win.
Regardless. it sounds like fun!
Keith
www.kaymac.ca