2003, we converted a 1997 Ford CF8000 commercial truck to our concept of an ExpeditionVehicle.
One of our early modifications:
* we added a 140-gallon 'saddle-tank' to supplement our stock 50-gallon tank.
We acquired this from Anderson Brothers Truck Wrecking in Eugene Oregon.
We sorted through piles of dozens of steel and aluminum tanks for the proper length and diameter, then sorted through brackets for the 'highest and tightest' to maintain our ground-clearance and reduce scrubbing on bushes and branches on the rough forest tracks we prefer.
On over-the-road ('OTR') semi-tractors with saddle-tanks -- such as your 110-gallon pair -- a simple hose connects the out-lets on each tank.
As you can imagine, a prudent operator would include a valve shut-off on each out-let.
As I understand larger engines, they draw from one tank while returning unused fuel to the other tank.
As you can see, fuel is constantly circulated:
* from the draw tank, to
* the engine, then unused fuel returns to
* the saddle-tank, and flows through the cross-hose to
* the draw tank.
Some engines use unused fuel to carry heat from the engine-mounted injector-pump to the saddle-tank as a sump, using it as a radiator to cool the warmed fuel.
2010, on the commercial trailer we converted to our concept of a toy-hauler, we mounted an additional 120-gallon tank.
In theory, our three tanks offer a range of Anchorage-to-Acapulco.
We prefer fueling in areas of low taxes.
Post photographs of your progress!