You will probably be a bit early on LB's, they usually swarm a week or so later, though you will undoubtedly see some early ones, they should not be really thick.
Unless you are doing serious daytime highway driving when they are at their worst, a radiator screen should not be necessary. Putting several coats of wax on your car right before the trip will be the best defense against paint damage (many people apply heavy paste wax and leave it unbuffed), also put bug-removal washer fluid in your tank, as that will make it easier to keep your windows clean. Some types of wax are better than others at making it easier to rinse off bug remains; shop around.
If you don't wax your car well and you encounter a lot of them, it will probably take serious scrubbing to remove them; they get sticky in the heat.