I would think that the main reason you want a propane system on your truck is to have lower operating costs. My guess is that there will always be readily available gasoline in the USA but the cost, as you suggested, could again be very high. If you install a propane system (or any alternative fuel system) on your vehicle, you should really plan on using it as much as possible to have the fuel savings pay back the cost of conversion.

Propane (and CNG) places high demands on an ignition system and most conversions at least use an electronic ignition system with top quality components. The ignition requirements for propane and gasoline are different so you can only optimize one fuel's fuel economy and power with a single curve distributor. Dual Curve used to make an add-on advance controller but many people weren't impressed with its performance. Generally, propane can use more initial advance but requires less total advance. If you just stick with the OEM advance curve, you could potentially have too much advance for propane at some operating points. A commonly-used, generic advance curve for propane systems is 14°+14°+14° (initial + mechanical + vacuum).

As for conversions, I haven't personally done any dual fuel conversions that I've provided links for. Conversions aren't hard to do but some are more complicated than others. As with anything, doing a good conversion comes with experience and care. However, it is also important to follow the regulations as they are there to protect you and others around you. I would also suggest that you get a local conversion shop's advice before you start and have them inspect your work BEFORE you put any fuel in it.