@hennesce thanks for reaching out!
The floor dimensions of your Big Agnes tent are 90" x 72"/62". The new Copper Spur footprint will be too short/narrow at 84" x 66"/58". Although we don't have a footprint that will fit exactly here are a few that are close to consider:
- Big Agnes Tiger Wall 3UL - this will be slightly shorter (88"), slightly more narrow at the head and feet (66"/60")
- REI Co-op Quarter Dome 3 - this is slightly shorter (85.6") and slightly more narrow at the head and feet (66.7"/61")
- Big Agnes Stillwater SL 3 - this is the same length as your tent, slightly more narrow at the head and slightly wider at the bottom (66")
The only other option would be to connect directly with Big Agnes to see if they still have the exact model of footprint to match your tent. Hope this helps!