From your description it seems that you certainly are taking him out often enough, I am not sure how long you stay outside but whenever possible he needs to be outside until he eliminates. It is also helpful to involve him in as many other daily activities outside as possible. You want to get away from the notion that outside is a bathroom and try to get him more comfortable with being outside, so as much play and even eating outside can create this feeling. Often, the attempt at crate training and then also trying to encourage elimination outdoors can be confusing and delay the overall progress. Pick one plan (yours seems best outdoors) and stay with it. Also remember he is just now becoming able to postpone elimination until he is in the chosen area. If you can keep him outdoors more you should make progress.