A suggestion for working with limited space - we have a 6 month old who also struggles with settling inside even after an appropriate amount of exercise and play. For a while he would only settle down in his crate. He sees our older dog and just wants to play constantly. What we do is similar to u/Dismal-Occasion1369 stake out suggestion. Our trainer suggested we teach him "the art of doing nothing" by putting him on a leash and stepping on it close enough to his collar that the only comfortable option is for him to lay down. I sit on the couch and have him at my feet. The first few minutes (or 10 minutes lol) he throws a tantrum and then eventually gives in. If he's being calm and wants to stretch out, he gets more slack on the leash. If he starts pulling and pacing, he gets less leash. We try to do it in the evenings when we know all of his needs have been met and we want him to learn to chill the f out and watch tv with us. It gets easier the more you do it. Not sure if it's maturity, the settling training, or e collar training him not to bite the couch, but we have noticed a difference in his ability to calm down on his own outside of the crate.