OK, SO there seems to be quite a lot going on here lol.
For a jump starter, I'd recommend going to Amazon, getting one of the ~$60 Lithium ion jump starters. They are compact and work well when the power goes out for charging things.
For the true issue at hand, those automatic bilge pumps have a bad habit of malfunction. They seem nice, but they malfunction at the worst time, either not coming on or coming on all the time.
First thing I would do is pull the boat and find the leak. That's more of an issue than the bilge draining the battery. Put it on a trailer and run some water inside from a hose, and see if you can locate the leak. It could be a thru hull or something more serious. Once that's fixed replace the pump and you should be good to go.
Moisture in a bilge will eventually cause some horrible problems.