Happy Turkey Day to all the WMT Jive (and non-Jive) Turkeys (and Tofurkeys if there are any in this crowd)!
I'm also enjoying this thread. I am only 4 harvests into my making wine from grapes-I-pick journey and have always done a second wine. My biggest takeaways are this:
Don't press hard on the first wine, think free run or close to it, leave your press behind and if you have to press at all (to fill a second carboy which is a gallon short, for example) just press a pyrex measuring cup into your pomace. That cup will fill with liquid and it is easy to keep the solids out or to strain that liquid before it goes in the carboy.
It will be better if you use a kit or pail wine rather than "sugar water with acid/tannin/yeast booster(s)."
But if you use a kit be really careful with MLB/MLF! Many of us co-inoculate, adding MLB to our picked grape ferments earlier rather than later. There are great benefits to this (to my rookie mind) in terms of temperature and available nutrients. But if you then add a kit wine to make a 2nd wine you may get undesirable results. Basically kit wines are acid balanced and adding MLB (from your pomace) to a kit is a really bad idea. That's what prompted me to make this post. Some kits are more forgiving (FWK) but it is still a bad idea, even with a FWK you will wind up with a flabby wine.
So either skip or delay the MLB addition if you are making a 2nd wine with a kit (vs. sugar water)! If you do it with a pail you should be fine, assuming the pail was not manipulated for acidity like kits.
Skipping MLB altogether should be done more often in wines from grapes! My best wine so far was last year's Grenache. I had no MLB. I then made a great 2nd wine with a FWK Syrah. The acid on that wine is so amazing that you immediately want another sip, I think MLB kills that. Everyone compares malic acid (which gets neutered into lactic acid by MLB) to a granny smith apple, and honestly many wines want that granny smith acidity.