Stumble, this sounds like the route to take but I'm not getting that last part. I'm picturing the bottom 20' of dyneema covered, including a core & cover tail of about 10' past the winch.
But then where is the 10' of empty cover coming from?
What keeps the strain on the dyneema and not on the cover where the winch grips it? A very small amount of load will be on the core, not much though. Basically the dyneema and the core get loaded a little, the core stretched but the dyneema doesn't (or far less). So more and more of the tension gets applied to the dyneema because it doesn't stretch. It's functionally the same as attaching a rubber band and a piece of twine the same length to something then pulling. Technically the rubber band will stretch minutely, but all the load is carried by the twine.
If you connect the top of the cover to the dyneema with the tapered bury inside the dyneema, then doesn't the cover end up taking all the strain from that point down, as the dyneema just slips freely inside it? No, the two lines act independently as to load carrying, the taper splice just prevents them from slipping past each other.
Or is the tapered bury at the bottom end, and if so, how to you anchor the top of the cover to the dyneema core so the winch doesn't slide it down? Or does the cover grip the dyneema adequately along its entire length? Too many pronouns I can't follow sorry. Basically starting from the top of the mast... The dyneema is attached runs down the rig to the block, close to the winch there is a taper splice where the cover starts. Then the core and cover run back together for some distance, where the core just ends but the cover keeps going. At the end of the cover, do use a reefing splice, or back splice to finish the end cleanly, you could just burn it, but meh.
Pardon my density here.
Sorry, I have been messing with tapered lines so long it's just second nature to short hand stuff.
Let's say the distance from the mast thru the deck hardware to the base of the winch (at maximum load) is 50' exactly. You want the cover to be over the dyneema past this point by at least 2' to make sure you really are at max load, and for a bit of a margin. So the first 46' is uncovered, the next 2' is the taper, the next 10' are covered, and the last 8' is just the empty cover.
What this does is gives you a big working section that is fully covered so the only thing that hits the winch is covered, and you get a long tail to make coiling easy when you are putting it away. If you decide the tail is too long, just cut off a piece, its cheap stuff so no worries.