I trailered my sled 70 miles this past weekend to ride. When I arrived to unload I noticed a bolt was missing. I looked closer and found the bolt was in fact broken off inside...man was I pissed.
Anyway, I thought the same thing. Here is my idea:
Drill out the aluminum to 1/2" and install 1/2" stainless steel threaded rod all the way through. Cut to length with locknuts. At least you could carry a spare in your trunk if one decided to break on the trail. Hell, the rod wouldn't even have to be stainless.
This is the second time I have had broken/missing bolts on the trail. It really pisses me off. There is no way Boivin could have "field" tested this and not found the same problem.