bed time

Now that it is cool out I am leaving the back door open all day and Moose has been spending a lot of time outside. He ends up lying on the pea gravel even though there is grass (not a lot though) and a cot type (Coolaroo) dog bed available. Since I have noticed a few rough spots on the sides of his paws from lying on the gravel I decided he needs something that he likes to lie on when he is outside. So, just to see if he will actually use any bed outside I put his favorite indoor bed out there this weekend and as you can see from the pic he still chooses to lay on the gravel! Though if I keep putting beds on the gravel maybe he will end up on the grass! A few times I have gotten him to lie on his bed by calling him over to it and once he is there he stays (not true of the cot type bed) so I am going to leave it out for a few days to see if he will decide it is better than the gravel before I buy him an outdoor bed...I am looking at a "snoozer" bed or a "tough dog" bed. Any suggestions?