I am confused about you feeling like there is not enough time to get calories in because with him only taking one nap, don't you have more time for meals and snacks than if he was having 2 naps?
I am still BFing as well with my 12 month DD and she is sometimes taking one nap. She wants to eat every couple of hours so I space meals and snacks about every 2-3 hours throughout the day and do a morning BF, a breakfast, then a snack, a lunch, a nap, a snack, dinner, a Bedtime BF and bedtime. She has water in a sippy and she did start on some whole milk at times during meals and snacks, but she pulls at my shirt and still wants a BF through the day and I am fine with that and sort of just go with the flow on any BFs outside of the wake up and bedtime ones that I know she usually wants.
Some of our snacks are on the go. I'll pack them for a trip to the park, the store, a friend's house, etc. The true meals I have her sit in her high chair at home or at a table if we are elsewhere so it's more like a real meal with everyone. She would probably eat all day long if she could!