My list each outing
Tire pressure, all straps, motor totor, all lights, swing pins for clips and excessive slack, inspection of tires and inner seals, basically a good walk around. Just these few takes only minutes though can save you hours and $$.
2 times a yr
Brake fluid level, tire inspection including jacking trailer up and checking wheel torque along with bearing movement. Disc pads., torsion arm bolt torque. All rollers, bunk board bolts. Bolts that hold axles up, caliper bolts, all items mention in each outing. Pretty much if its got a bolt or nut it gets a wrench put on it. These few not counting boat & motor inspection take me a couple hours but can save one thousands!
Im sure ive missed a couple. In my 32 yrs of boating ive been on the side of the rd a few times. Its never no fun. We live we learn!