Is it possible to make guacamole without acid

In answer to your second part, no. If something is not acidic enough for water canning it seems it doesn't matter how long you process it, it isn't safe. This is the reasoning all the cookbooks I've read provide for adding a teaspoon of lemon juice to each pint of tomatoes.

I would therefore use this strategy:

• get things to the right pH for water or pressure canning as a separate first step. (Fruit will generally be ok, tomatoes need lemon juice, pickles will be ok, etc)
• check the processing time for pints and quarts of various things (jams, fruit, pickles etc) and look for the pattern: is it consistently 25% more time, or 5 extra minutes? Work out the pattern.
• repeat for hot vs cold pack: do you halve the time, or subtract 10 minutes, or what?

Now armed with a hot-pack pints recipe, you can adjust it for cold-pack quarts or vice versa. You should also, in poring through these recipes and charts, have come to understand various categories (fruit, jam, pickles, nonpickled vegetables etc) and be familiar with what times they need. Then faced with a chutney, conserve, or pickle that isn't on anybody's list, you should be able to choose what category it most likely belongs to, and safely pick a time for it.

White wine in tomato sauces adds:

• Some acidity, but tomatoes are quite acidic as well
• A touch of fruitiness and flavor
• Alcohol, which does not all cook off, which can enhance the perception of the dish due to some flavor molecules being alcohol soluble, especially in tomatoes

Since you are avoiding alcohol itself, some of the options you might use are:

• Simply omit the wine. The dish may not be quite as good, but it will still be good.
• Use a splash of verjuice (un-fermented grape juice) if you can get it; this will give you some of the fruity and acidic qualities, without the alcohol.
• Use a splash of white wine vinegar (unless you are concerned with the trace amounts of alcohol that may persist from its production); this will give you some acid, but you are not likely to use enough to add any significant fruitiness.

Since you are specifically avoiding alcohol, you necessarily lose the flavor enhancing effect it can have, but a good well seasoned dish will stand up without it.

I would suggest you make your sauce, and if you feel it lacks brightness, to try cooking down a little white wine vinegar or apple cider vinegar and adding it; otherwise, leave it alone.

And of course, taste as you are cooking to season it well.

Again, as one component of several in a lasagna, which is all about the integration and balance of all of the components, I wouldn't worry about it this overly much.