Welcome to the forum
Let me sum up some of what you said and let me know it it is correct
Dome light didn't work but all other lights did and truck started OK
A few days to a month after that.................the truck wouldn't start, but all lights and gauges worked(except dome of course)
A few days or month after that..............., the dash stopped working so no power at all
First, Dome light is not related to anything
The 7.5amp fuse was probably the Battery Light fuse which TURNS alternator on and off, no battery light when you turn on the key means NO alternator, it is OFF.
So thats why battery went dead.
"one click" when you try to start is almost always a loose or bad battery cable, 99.9% of the time.
BOTH battery cables are needed to get enough Amps to start an engine, not just positive.
So clean BOTH cables at BOTH ends.
Car(truck) batteries have thin plates inside, this allows them to provide full amps to start an engine, thats is what they were designed for.
Then be quickly recharged after starting.
But thin plates are very bad for long term use, slow drains, it ruins them to run them down
Deep Cycle batteries have thick plates, they are made to provide a little power over long periods and drained down then recharged.
If you are using your car battery while engine is off then you have the wrong battery and will just ruin one car battery after the next.
You need to get a Deep Cycle battery, it will have enough fast amps to start engine, but will cost a bit more.
And you need to get a Volt Meter
Vehicle battery needs to have 12.3 to 12.8volts
12.2 and lower is a bad battery
12.8 is new battery
12.3 is a 5 to 7 year old battery
After engine starts and is idling battery should show 2 volts higher than "at rest" battery, so say 14.5volts, 12.5 + 2
Then after 10 minutes or so of running and at idle again battery voltage should, 1.1 volts above "at rest", so 13.6, 12.5 + 1.1
If you charge a 12volt battery with 14 volts all the time it will ruin the battery, so voltage regulator does a "fast charge" for 5 to 10 minutes then lowers it down to "safe charge"