Ducks and Geese. Help please!!

Hi everyone!! So I have 2 Pekin ducklings, and I am interested in getting a toulouse gosling. Can I keep them together, or would they need to be seperated even if they are raised together? Also, I am building my chicken coop this weekend in addition to their run and a seperate run for the ducks/goslings. I was planning on doing a 8ft wide x 12 ft long run for the ducks and geese. Do you think this would be enough? I am also building a pond and their own little house...

Thanks!