</font><font color="blue" class="small">( Large trucks are required to pay taxes (via fuel purchases) to compensate for the larger amount of damage they do to the roads. Since pickups are not required to pay such taxes (at least not here in WV) there should be no issue with using either type of fuel )</font>
</font><font color="blue" class="small">( I'd say you're right on the money here on this.
Also Since the tax is a State or Federal highway use tax
the only time it's taxable is when a vehicle is driven on a US or State Highway;
therefore the tax would not apply on vehicles operated on county and township roads or city streets. )</font>
Not sure how it works in the Northwest Territories, but down here in the lower 48, trucks pay an annual Road Use Tax in addition to the tax paid at the pump. And there is no evading either because the truck is on county or township roads, etc. The are also required to prorate the amount of fuel tax based on the mileage driven in any particular state. For instance, if a truck buys fuel at the state line, then spends most of that tank of fuel driving in the other state, the other state gets the fuel tax--not the state where it was purchased.