I don't really have any help, only shared misery. Last year, like you, we didn't mow our fields of grass, and they promptly took over our garden bed. This year, we were better about mowing, which helped a lot in controlling the spread of grass. We also used mulch, which carried seeds like yours did, and also attracted slugs
. So, while grasshoppers ate your garden, slugs ate mine. We bought ducks for our slug control, which
should help a lot. I already see a lot less slugs. Ducks/guinea hens/chickens could also help with your grasshopper problem, I would think. Guinea hens might be better since they are from hot,dry climates, and I think are more disease resistant than
chickens. They also are supposedly better at avoiding predators than
chickens are, so you wouldn't have to worry as much in managing them, since you're only able to be there every few weekends. www.motherearthnews.com/homesteading-and-livestock/raising-guinea-fowl-zmaz92aszshe.aspx#axzz3HJArd94q
The only sure suggestion I have from expereince is to make sure to mow. It really does help a lot. Also, planting a bunch of things that can compete with grass (for examples strawberries fit that niche here, but I don't know what would in your area) should help to.
Most of all, know you're not alone! I even am at my homestead 24/7! (...though carrying for a colicky baby severely restricted my ability to garden...)