Long Distance Custody?

My ex and I are butting heads over a custody agreement. We get along fairly well and would like to figure it out on our own without involving the court. Our situation is made particularly difficult because I live in Oregon and he lives in Maryland, we’re literally on opposite sides of the country. His mother is upset because I asked for 20% of his income to go towards child support. She believes this is way too much. They also believe I haven’t offered enough visitation. I offered my ex Christmas and Christmas eve, a week during the summer, a week during spring, and an open invitation to visit Oregon and stay with us whenever he is able to. I also plan on visiting Maryland when I can because most of my family lives there. I don’t feel I can offer much more time because I need to work! I can’t take off for a week every month to fly across the country! What are your custody agreements like? What would you offer in my situation?