Thanks for all your help. It's fixed now. It's not even worth trying to do it without buying a flare wrench (I bought a Craftsman and ordered a Snap-On from eBay to keep in my toolbox).
I had met a mechanic turned broker while I was working on my boat a couple weeks ago. I walked into his office with a 3/8 flare wrench in hand and he says to me rhetorically, seeing the wrench in my hand, "did you break a trim line?" He helped (well, did) with the repair. To access the rear fittings on the line there's a zinc block held on by two 7/16 bolts at the bottom that has to be removed, taking care to ensure that the gasket remains undamaged. If you cannot get the hose fitting to break free, while we didn't have to do this, he explained to cut the line and use a socket. He also mentioned that what I see with the collars on the hose fittings being split is normal and doesn't indicate that the lines need to be replaced and that it's always the "up" lines that fail due to the higher load.