Need some advice from those who tow a lot.

Just note that that mirror glass is not heated and you will have to break your old glass to get the backing/mounting that the glass mounts on if doing the job correctly.
However you could just stick it on top with sticky pads??

If you can see the back edge of the trailer then surely there is no issue? The standard mirrors easily meet the 4m wide at 20m visibility requirement. If you want to change the mirrors then fair enough, but there is no legal requirement for you to do so.

All I want is to be beyond reproach in the event of a vosa roadside check or worse a collision, if I add additional mirrors even if I am already legal then there's one less thing that can be used against me, and yes I know that sounds like paranoia.

That's gotta be wrong hasn't it?? I'm not sure I could see 20m behind my work pickup wimithout towing anything God help me if I need to use that to tow the jimny anywhere!

As an ex lgv driver I know what 11/60 means. VOSA are always looking for a likely "pull".
Anything that looks slightly commercial and a bit tatty will be pulled and that includes farmers etc with trailers that don't get used much also old landrovers and transits.
Fitting those mirrors will minimise another reason to get fined or points.
Bet not many people know it's also illegal to leave towing mirrors on the car if you are not towing a caravan/trailer!!

www.lifesure.co.uk/blog/2013/06/caravan-...re-you-know-the-law/

Basketcase, I think you've interpreted it wrong. You need to be able to see a point 20m behind where you sit and inline with the side of your vehicle/trailer. At the same time you should also be able to see a point 4m to the outside of the first point. E.g. at a distance of 20m, you should be able to see and area 4m wide.

I just checked with my Jimny mirrors, and at 20m distance I can see an area 12m wide! So they far exceed the legal requirements, as long as your view in the mirrors isn't obstructed by the trailer. If the vehicle you tow the Jimny with is wider than the Jimny then there is no problem.