The Three Thieves

Tom stole a mug worth $3000. Dick stole a jug worth $5000. Harry stole a rug worth $8000. To escape, they had to cross a river in a boat which either held two people or one person and one item. No person was to be left alone with objects worth more than what he stole, but two people could act as checks for each other, and could be trusted with objects worth more than what they stole. How would they cross the river, given that all three could row?

(From Henry Dudeney's Amusements in Mathematics.)