I just had my front cap painted. Could not get a paint code from Crossroads as they outsource the caps and don't have any information on my Sunset Trail.
The autobody shop that did mine had their paint supplier come around with a scanner and they found a color very close to the original. You wouldn't know the difference.
Check with an automotive paint supplier to see if they have a scanner. You will probably have to take your trailer there but it doesn't take long to do the scan.
2014 Sunset Trail Reserve ST25RB
2013 Toyota Tundra Crewmax Platinum 5.7 Tow Package