If the memory of your father's truck trumps the fact that it's too small to do much with any size of TC, go for the easiest, cheapest way to keep the truck and do some camping.
There are still a lot of questions to broach. How many bodies are going camping in a potential truck camper? If it is just one, get the cheapest used lightweight pop up you can find, especially if you are a fix-it guy. Retired firefighters have a lot of life left, so i'm assuming this would be a good way to see if you have it in you to try out TC-ing, and which way you go from there. For most small TC owners, there is a subtile paradigm shift toward something larger, more capable and more comfortable for long trips. This comes right along with age. Then again, some of those large tear drop looking trailers look very interesting and we saw a lot of them in the last 12 days on our Oregon Coast trip. Do you have a lot of camping experience? If so, you know the value of choosing the appropriate vehicle. If not, check into a used Class C and keep the Taco.Just remember the huge advantage of having a truck camper is its multiple use: camper and hauler. If you don't haul anything, then it doesn't matter.
We just got back from our annual 'kids and grandkids camping trip' on coastal Oregon. It was 63 degrees much of the week along the shoreline. On our return trip through Redding, CA it was 114 degrees. Our adult kids rented a 29 foot class C. It sleeps 8 and got 11 mpg to boot. Chevy 454 F.I. on a 3500 chassis. They have no space to park any RV during the year living in San Jose, CA.
My son (47) is now living alone and is contemplating joining the Mercedes Benz Sprinter Van living club. Now with 4WD they are a great place to build a stealth RV. It is still multi purpose.
So many ways to go. If you do decide to go with a rental RV just for a week or two a year, just remember jefe's dictum: "Nothing off roads like a rental rv."