The exemptions listed on the LEZ webpage also show you can convert to spark ignited gas- no idea how that is done, or you can fit a particulate filter, both sound pretty expensive.
Off road vehicles such as tractors and farm machinery are exempt- which brings a real narrow loophole for Aussie spec CJ340B mindies- they are fitted with the 5.38 ratio diff's and the power take off, both which were intended to be used to run agricultural accessories.
Ages ago, I saw an american bloke selling early promotional films on ebay - showing CJ3B's fitted with plows, mowers, snow plows, grader blades, post hole augers, rakes and all sorts of ag. uses.
If you didnt mind having the mounting points for a simple plow bolted onto your mindie- and the hydraulic pump to run it off the power take off- thats another option you could try.
You could hook a power steering pump to the PTO to operate a ram to lift and lower the plow.
A plow or rake would be the easiest as they only need lifting and lowering- no rotating parts.
then its both (sort of) historicly agricultural
If you can get the ok from the LEZ wallahs- the pump, mounts and plow/rake are pretty easy to put together- the hardest part is finding a big old plow to cut up for the plowshares to make one about the width of a mindie- but these big old plows are often found rusting away on farms.
maybe someone over your way can contact the LEZ mob and ask the questions- bit hard for me being on the sunny side of the world
come on fellas- dont just roll over- give it a fighting chance and think about ways of beating them with thier own rule book