Sorry to respond so late, I'm not understanding the comment as to that tank not being made or suitable for diesel. Petroleum fuel is the same in any tank that is made for fueling.
Now if you mix fuels, you are going to have engine operational problems, not tank problems.
If you've had to remove the tank anyway, you may just be stuck with the potable container carry method only.
Dan & Loretta, US Army Retired Aero Scout Pilot
2012 Fleetwood Providence 42P Class A/DP
Spartan Chassis, 8.9L Cummins 450HP