Depending on what system you go with, it can be very easy to remove.
A Powershot system for example requires no permanent modifications to install.
It can be removed without evidience in about 30 minutes.

Propane injection will give you about 100 miles further range perhaps a bit more on your diesel tank, based on 5 gallons of propane.

So if you are looking for increased range, overall, it would help, but not as much as the larger fuel storage, but then again, it won't be near as much fun