That is the biggest problem; where to get the oil from and where to return it to the sump. I was thinking of 1/4-1/2 of the left radiator area used as an oil cooler and the remanning radiators with a thicker core. Or a Setrab behind the current left rad. I had a DR350 back in the day with a nice oil cooler and my current DR650 has one. I remember Honda had one on their XR's around the steering head but it was pretty small.