Many times over the years I've knocked my brains silly trying to get trailer lights working properly, especially at the beginning of the season, only to find it was a ground fault.

You're slightly wrong in assuming that the cheaper independent bulb trailer wiring converters will upset the bulb out sensor. If you go to the trouble of running a wire for the brake lights all the way up to the front to attach ahead of the bulb out sensor (like at the brake pedal switch) and also grab the parking lights off something harmless like the license plate lighting (not on the bulb out sensor) then all will be well. As I've mentioned many times, the biggest problem with those adapters is that they provide as little as 5 volts through to the trailer brake/turn lamp filaments so they won't be very bright. The proper solution as you know is to use a powered adapter. I know these often cost over $50, even on websites (counting shipping), but if you shop around at places like RV dealers or wholesale auto suppliers you should do better, like under $40 (even in Canada, eh).
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Dave -940's, prev 740/240/140/120 You'd think I'd have learned by now