I feel your pain . I have ten trailers and only five are on road. My wife says I have a thing for trailers but I look at it like one truck can do a lot of things with trailers and no extra insurance and taxes.
You can solve the expensive car electronics failures by putting a in line fuse on the hot wires at trailer plug - takes three.

Sparkplug -
Have a Stihl 031 1978 vintage been using for 37 years - never done anything but one electronic module and spark plugs. loan it out one day and they broke the throttle hold button and something in carb - $180 later running again and will never loan it again-
any time I get askedI just say broke and they will need to take to shop to fix before using-that stops it quick. I really like that saw and bet they don't build em that good anymore.