Having too much time on my hands.....I decided to make use of the wasted space behind the left aluminum pannier. I already had a PVC equipment owners manual tube laying around the shop so that became the new tool holder.
Messing with some scrap aluminum gave me this mount:
which mounts to the hard bag rack
from the rear:
Of course, after I took the photos I found that the tube had to be moved about 1/4" inboard to clear the upper bag mounting bar. That just resulted in having to drill and tap one hole but I was too lazy to take a photo of the new hole. Everything works now and I can carry my tool roll outside the bags.
Peter Y.