The next progression in this will be getting him used to this concept everywhere he is, not just in my room. First, we'll begin indoors where there's less distractions but still more "environment" for him to deal with and a little more "terrain" with stairs and the like.
First, we started in the hall and I had him retrieve the bone several times using "go get ___ " with the blank filled with "hueso" the name of the bone (I haven't forgotten the "canine programming language" idea). I also threw in the "give" cue today. So I said "give hueso" instead of just the generic "give".
In addition, we played around with the bone and did the same "hueso! hueso!" as before when starting the immersion with the bone. He responded as eagerly as always, and he's learning the constant is the object.
After the bit of play, I put in another cue, "take", this time calling for "take hueso" with the bone in clear view in my hand. Now that he has it in his mouth, he can get some practice carrying it around (something we need to get back to...), and can start doing things while holding the bone, like opening doors. If he has to put it down for now, that's fine as it gives another chance for him to practicing "take" and another chance for me to use "take hueso".
Eventually, we'll take this outside and continue the same things (sans opening doors, of course). Being outside will add challenge for us both, especially now with kids likely to be everywhere with school out for the summer (here's hoping for a lot of family vacations in the neighborhood!)
Also want to add in "hueso" (or any object name) for cues like touch and paw. This might give him another way to indicate the object and another action for him to perform on it during shaping practice.