For your situation I would recommend Duragloss Aquawax. It's technically a spray sealant and it lasts a few months. It's good enough to work with and cheap enough that you can use it with every wash. Similar spray sealants from Meguairs are also a good option and can be found at Wal-Mart. Unfortunately there is no spray on wipe off polish that I know of, you'll have to use a polisher if you want to truly polish your truck.