As others have suggested, avoid putting a hole in the boat to begin with…
One thing I'd suggest, not just for ice, but for anyone venturing offshore, is to configure a custom fitted collision mat from a very tough fabric such as Stamoid, that will cover the entire bow/forward third of your hull to 18" or so above the waterline, pre-rigged so that it could be put in place in a matter or minutes… that MIGHT give you a bit of breathing room, to begin effecting a repair…
A great amount of luck will likely determine the outcome of your intended voyage… The greatest risk you will face, by far, is getting caught by moving pack ice… If you were in a steel boat, you could have a prayer in such a situation… A fiberglass boat, however, you're likely to be crushed like an eggshell, there's good reason why most people would not consider attempting the NW Passage in a boat such as yours…
Frankly, I don't see how you will be able to carry the amount of fuel required, not to mention the stores should you not make it through and be required to winter over… One of the main problems with going with a small boat so heavily-laden, she will be unlikely to "pop up" above the surrounding ice in a crushing scenario, unless you start tossing your supplies onto the ice… Not good…
Someone suggested an extensive shakedown of a season in Greenland, that's excellent advice… Given your location, a summer in Svalbard could afford some hints as to what you might be up against, but I doubt you want to hear that…
Frankly, I think attempting such a voyage in a fiberglass boat, with an engine about which you "are becoming increasingly concerned", is incredibly foolhardy… Probably just me, when I think of voyaging "on a shoestring", I think of places like the Bahamas, Mexico, and so forth… The Northwest Passage? Well, not so much…
But, since you are budget conscious, I'd suggest you go the route of two of the most exemplary sailors I have ever had the pleasure to meet, and go without an EPIRB… Show the commitment of Tim and Pauline Carr, when they decided to venture into the Antarctic Convergence and South Georgia aboard CURLEW, they fully realized the magnitude of their choice to sail there, and the inherent unfairness of expecting any sort of rescue, the severity of the jeopardy they might be placing upon any potential rescuers… Why not demonstrate a similar appreciation of the magnitude of the risk you are taking, and prepare yourselves - to use Blondie Hasler's famous words regarding voyaging without a radio - "to drown like a gentleman"…
Frankly, I think your plan betrays a profound ignorance of the sort of things you might encounter on such a trip… Not to say it can't be done, of course - with the right amount of luck, no doubt it could be… I haven't been that far north, but I have made it pretty far south, and it's not the sort of place you want to have to depend on
LUCK in order to survive…