Hi MatO and welcome.
As a SIT, the Outback has a plenum of air inside to provide lots of bouyancy. But if you capsize with a open hatch, there is no positive flotation -- it could theoretically fill up with water.
A lot of users buy these "pool noodles" and drop them inside the hull. Apparantly you can get these in a variety of sizes that provide positive bouyancy up to 300 lb., even if the hull were breeched by an iceberg or a hungry shark!
I have the Adventure model so cannot speak directly to the Outback. The Adventure can be righted and remounted, even with a sail, unassisted. However, there is a bit of a technique and practice is highly recommended. In your cold waters and especially with extra gear on, you undoubtedly have limited time in the water. Aloha Dan
some time ago described a remounting rig for his wife -- this should work pretty well for any kayak. You might want to check out his earlier postings for the specifics.