If you can swing the end of August and very beginning of September, then you are good to go in Colorado. Elk and antelope are over the counter with antelope actually opening near the middle of the month of august.
No restrictions on aliens, but you must have a CO hunter safety card or something reciprocal. Not needed if you were born before 1950.
You can also Hunt deer but would need to apply by drawing by early April and would have to select a specific Hunt area in your application.
If you have any other questions, feel free to shoot a PM.
your hornbow would be legal as long as it draws at least 35#.!!!