Can you patch it from the inside? Since it's a hole/crack you can likely get things go into the hole/crack and puncture the inner tube.
If you want to chance it, how about filling the gap with some kinda elastic glue (gorilla glue? or just epoxy/superglue? whatever) so that it stays shut...and use some puncture repair patches on the inside to hold it closed for good measure, adding a layer of resistance to anything that still goes through.
Can you patch it from the inside? Since it's a hole/crack you can likely get things go into the hole/crack and puncture the inner tube.
If you want to chance it, how about filling the gap with some kinda elastic glue (gorilla glue? or just epoxy/superglue? whatever) so that it stays shut...and use some puncture repair patches on the inside to hold it closed for good measure, adding a layer of resistance to anything that still goes through.