Is it a roller trailer?
If so are the rear rollers fully back on the chassis? On mine it's set up such that when fully "in" they are pretty much level with the rear roller. If they become a problem on recovery, they will be the least of my worries!
I have experimented with leaving mine further out (I will be fitting LED submersibles soon and so I wanted to see where it would become a problem). I can leave mine about 18" protruding behind the rear rollers and (apologies if you need to read this twice) because the bow slopes up and the boat sits low in the water compared to the rollers, the "toob" bit of the bow curve usually meets the rollers anfd engages long before anything that is deep enough to meet the ligting board brackets gets anywhere near.
Having then hauled the boat on & motored the engine down to it's block, I can now leave them there & still be "strictly legal" on the road WRT light height and protrusions.
I do agree with Maxhar that it is strictly illegal to have lights so high (on the A- frame) and I also partly agree with Thomas in so much as that the view is usually partly blocked by the engine, which practically is not good.
What I am in the middle of doing is taken two LED submerible clusters, sat 18" back form the roller. Number plate is (will be) on a short board that will be sat atop the engine leg and held down by the engine securing strap. At the front, the plug goes to an IP rated breakout box (I never know when it might get swamped & keeps the connections dry) which breaks out to the two L & R clusters, and takes a feed to the 'Plate lamps & a high level brake light via an extension that is fed through the boat like the current board cable is. The number plate lights are fed via a Bulgin Buccaneer (to keep the breakout box watertight).
So, Road lights are at a legal altitude (and no engine in the way to block them), number plate can be seen and I get a bonus of a high level brake light on the trailer ! I'll post a piccy thread once it's finished.
tail lamps / indicators 350mm<height<1500mm
fog lamps 250mm<height<1000mm
triangle reflector 350mm<height<900mm
Remember - check with current regs before fitting, and remember there are other positional regs on the distance from the edge / cetreline of the trailer and other lamps as well.