Covering it will plastic will heat the soil and kill all your seed. You definitely have a challenge there. I'm wondering if you could sprout the seed indoors in flat trays and plant those in the yard??

That could be done, but will take me 5 years to fill 40k of yard :D

Don't plant more than you can care for. A method that works for establishing pasture grasses where resources are limited is to seed strips and let the grasses spread naturally.

If you seeded an area that you could care for this year and got it going, then next year seeded another ... you would get a lawn eventually. And the clippings from the first section could be composted onto the second one, building your success.

Have you considered using some of the other "grassy" looking plants that normally grow in sandy soil? Dune Sedge, some of the "ice plants", etc. are going to be easier to establish. A mixed "meadow" look is easier to attain.

http://www.laspilitas.com/nature-of-california/plants/carex-pansa says that Carex practically REQUIRES near-beach sand. Sounds like a better idea than Bermuda grass.

Thanks for the input lazygardens, but that Carex wont work for me.
Carex pansa is native there, forming little clumps separated by feet of open sand, kinda like a dog with mange. Will not work as lawn.

The step by step would work. Do what i can take care off.