Hey @MotivDev,
We solved this issue with this solution. Note we changed the small copper caps to one big one with thermal compound underneath for ease of install.
We have 14 fins in the field that have been running 24/7 with this solution. Granted they aren’t in conditions where it gets anywhere near 58C outside so they only have to disperse their own heat.
I am still trying to release design files for the lid we designed to deal with this issue.
In my testing, I think I have eliminated the possibility of a USB overpower problem by creating that problem with chained hubs and not experiencing the same issue set. The problem wasn’t heating the fin was generating but the heat that was flowing in from our USB devices. However, your use case will chance this as our USB devices generate all their heat within 1cm of the fin.
If you have any questions about how we designed around this, please let me know as I have come to hate thermal issues. 
Cheers
-Thomas