I check most fluid except trans and axle before heading out and then just engine oil at each fuel stop. Other than that I make absolutely sure I have a socket that fits the truck wheels and the trailer wheels, 6" extension and 1/2" breaker bar.
When hitching trailer I double check everything and then do a walk around looking at each door lock and jack making sure they are locked and Up. Then roof vents closed, awning in UP position and arms strapped closed. Steps up and Door locked. Sewer cap on and valves closed.
I only check air pressures first thing in the morning and don't fret if it's down a pound from all the previous mornings checks.