+1 for DIY
Shade tree mechanic here, done multiple HC replacements and they are pretty straight forward. Would advise getting a good manual though, as one can come across some weird fasteners especially the plastic kind. You tend to have more room working in a pick up so that's good. Would suggest double checking with a truck forum for advise from those who done this repair before to avoid any pitfalls. Count on it being a weekend project for an amateur, and you'll hopefully have time to spare without being stressed. I would also suggest that you prepare a "plan B" before you start in case things do not work out in the time available, life is like that. For less than $10 you can usually scrounge up enough to work a bypass to keep the truck running albeit without the heater until you can take another crack at it.
Good luck bro!
What a lovely bunch of coconuts.
Better to be a fast mule than a slow race horse.