Originally, my first thought was the Shimano dynamo hub plug, but then I remembered that although it will slide over the prongs of the Schmidt, the plug is too fat/blades too thin for good contact.

What you can do is leave the spade connectors connected to the hub and then install some other connectors several inches down the line that are intended to be seperated/reconnected easily. If you had the proper crimper, Anderson Power PoleŽ would be my go-to since, my other hobby is HAM radio, I have drawers full of 'em. But any waterproof automotive electrical connector along those lines would work just as well.

I would take the time to solder and then shrink wrap whatever connection terminals you decide on for durability, in any case.