you've got the right idea, just set it up and record from any random source (mics in front of stereo, line out from stereo, etc) for as long as you can, see what happens when it gets to the limit...see how long it takes to stop/start a new recording, find out what the limit is as far as time goes, test battery life, etc. best to do it with your whole rig so you also get practice setting up/tearing down, but will also work with just a line in to make sure it does record satisfactorily, ie. no pops/clicks, dropouts, etc.
keep us informed! and good luck!