Susan and I are in very similar positions. I have a detatched garage modified studio as well and always encourage my clients to obtain extra cardio time. We are like a giant family so noone usually complains about others using the cardio equipment during their session. I face all these machines toward the wall so everybody feels appropriately focused on their own task at hand. I just request that they schedule the time to correspond with a time I am already commited to being there. When all parties agree, its a go.