I don't think there's a huge amount of cooling going on with the factory oil tank. Lines are effectively insulated, tank is smooth, covered, and out of the airflow. To test that theary one could ride it hard to get oil temp up then take temp readings at pan, oil filter, and tank/dipstick. I'd guess there's not a huge variation but of course I could be wrong.
Also, I'm wondering how the oil pump is driven with this extension. There are no idlers or anything like that shown. Nevermind I'm dumb, the pump mounts to the top of the extension piece and the pickup portion mounts to the bottom.
Regarding oil routing, the adapter/spacer between pump and pickup can just have a passage open from the tank pickup to the sump pickup before the screen and the return open to the sump. Passages to the outside of the engine may or may not be blocked off internally in the spacer, but of course must be blocked off external on the engine. Seems simple enough.
Neat, but I don't see the point aside from aesthetics.