So call me nuts. I listen to Christmas music at odd times all year long. When it gets hot outside, I turn on the air conditioner and make Christmas ornaments. When the garden is doing well and summer produce is abundant... I think of Christmas! As in soup mixes (for gifts, of course!)
It's very inexpensive to dehydrate a variety of summer vegetables if you grow them yourself or can buy them inexpensively. I've dehydrated squash and onions on trays in the car when it's in the sun. Any tray with a net or screen bottom can be used anywhere it gets very warm and can be protected from insects and birds. A light cloth will do it if you can clip it to the edges of a tray and keep the tray off the ground where insects will find it.
I wrote a article about dehydrating without electricity that may interest you:
Simple Dehydrators and Other Ways to Dry Food
When you have a good variety of dehydrated vegetables on hand, take a cup or two of each kind or mix them according to your preferences. When you have all the vegetables mixed well, distribute them in individual containers or plastic bags. Remember that dehydrated vegetables are about 1/8 to 1/2 of their original volume, depending on the vegetable, so a cup of dehydrated food will be anywhere from 2 to 8 cups once they're rehydrated.
If you have an abundance of zucchini or yellow squash, powder them in your blender or food mill after they're dehydrated. They make great thickener for the soup mix. Just add it to the individual packages.
Note: Try it before you package up a lot. Make sure you like the combination of vegetables, and make adjustments to that and add spices or other flavorings.
If you're like I am, you'll want to find pretty packaging and maybe tie them with Christmas ribbon. But if you're not thinking that much of Christmas, just think of how good a vegetable soup from the garden will taste when the snow flies.