I just use commercial bug and black streak remover along with a good soft brush dipped warm water with car wash(soap). Removes them nearly all in one shot and they are designed for the paint. Can find it at Wal-Mart or your favorite RV shop.
Works great on anything that gets bugged (Front cap, truck, awning bars, etc).
Found using the bug remover with a 2-5 minute soak really works the best, scrub, then rinse, even if you use a high pressure wand to rinse with.