Here is what worked well for me. Wash outside of it really well, I scrubbed it with a vegetable brush. Cut in half.
Scoop out middle with large spoon. Cut squash in large chunks.
I then used my turkey roaster, but you won't need anything that big unless you are doing a big one or several. Add just enough water in bottom to keep from sticking and create some steam. Cook over low to medium heat (whatever it takes to keep it cooking but not burning) until the flesh is tender. It won't take too long.

Take off burner, remove lid and let cool until you can handle the chunks. Then scrape off the flesh with a spoon into large bowl.

I used the food processor to puree it smooth.

Pack into containers and freeze. I put what is called for in a pie recipe in a single container.

If you have a place to store them, they might just keep over winter without processing. That is what I plan to do.
I will just work up the ones with bad spots that I think won't keep well.