Need a little help in the plumbing department!!
I can recomend the idea of using a smaller second pump with check valve. If there is no room for a second pump you can install a non submersable pump. This type of pump can be located neerer the exit point of the hull out of the bilge and even above water line. The suction hose leeds from the pump down to the bilge. All that is in the bilge is the hose and strainer at the end of the hose. The bilge water is sucked up to the pump befor it looses a prime and little residule water is left in hose.