Wow, that's a lot of space. It's not to late to plant plants. It's getting pretty late to plant perennials from seed. They are usually slower sprouting and slower growing. You didn't say, but I'm assuming you want perennials that will keep coming back and get themselves established.
So courtesy of the LadyBird Johnson Wildflower center native plant data base https://www.wildflower.org/plants/ here's a selection of all the wonderful native wildflowers you have out there. These are all selected to be tolerant of desert sun and dry conditions:
yarrow, dogbane, butterflyweed/ milkweed, milkvetch, bouchea, indian paintbrush, poppy mallow, mariposa lily, sundrops, evening rain lily, coreopsis/tickseed, coneflower, Englemann's daisy, wild buckwheat, gaillardia/brown-eyed susan, liatris/ blazing star, lupines, four o'clocks, blackfoot daisy, bee balm, devil's bouquet, penstemon/beardtongue, mexican hat/prairie coneflower, black-eyed susan, perennial salvia, compass plant, globe mallow, goldenrod, desert zinnia
If you find a good local nursery specializing in desert plants you should be able to find a lot of these. Some you might have to order on line if you wanted them (google them to see pictures and info). Plant a bunch of these and you will get a prairie meadow effect. Many of them are attractive to birds and butterflies.
For more diversity, especially with so much space, you can make a more balanced system by including some grasses (e.g. indian rice grass sideoats grama grass , blue grama, buffalograss) and shrubs (prairie sagewort/artemisia, cholla, sotol, mescal bean/ New Mexico locust, ocotillo, yucca, esperanza/ yellow bells)
All of these are tough hardy plants that ONCE ESTABLISHED will be very low maintenance, but remember that everything takes some care to get established. And the trouble with planting when it's already hot, is that the plants don't have much root system yet, so they will take more watering than they will later.
It will be a time and money consuming project to plant that much space. I'd start by putting in a few grasses and shrubs scattered along it. In between / around them put some of the wildflowers, widely spaced. Then mulch everything very well. In coming years what you have planted will spread itself, and you can fill in with more plants.