I use the core from the toilet paper role to slip over the covering paper to keep it from unrolling,when i'm cutting pieces and just leave it on when i'm done.

Not sure what you are referring too with the term "covering paper"? Shelf paper maybe? Any way I use a small piece of masking tape on my "open" rolls of Monokote, and related products. . Works for me.

Are you referring to using silkspan. If so it is in really short supply and the replacement for it is sadly lacking. A decent substitute for Silkspan is a product called Polyspan. It is a very light fabric that is applied in the conventional way that silkspan is applied. You do not wet it to apply and you can do light shrinking with an iron to remove small wrinkles.A covering iron is the preferred method. High heat guns are to be avoided as you can burn the fabric. You finish the same as you would silkspan with clear dope. Do not sand the doped finisfh funtil you have at least 4 coats on it. Failure to not observe this practice will result in some serious fuzzing on the fabric that will not disappear no matter how much you finish sand it. Like all covering products there is a learning curve but once learned you will have a lightweight durable covering that will last a long time.