Joe,
I'm having the same problem with my son, he's just turned 17 this month....
I have been looking in depth for over a year now at the best (cheapest) way to do it so here's what i've found...
Insurance quotes are all different for different people, just because someone else gets a good quote from Churchill etc it doesnt mean you will even if all the details are nearly the same.
so the "try X, Y and Z they were cheap for me" doesnt work... (I've tried it)
Apart from your age, the car and your postcode are the main factors in the quote price.
Adding him onto my policy as a named driver put my policy from £200 to £3000, they seem to have sussed this dodge out and will not pay out on a claim if they find out the named driver is actually the main driver..
For my son, all the popular Group 1 insurance, low spec, smallest engine cars such as Clio, peugeot 106, corsa etc resulted in quotes around the £3000 mark. (he stays in rural Scotland, low risk postcode)
The cheapest quote I could get was for a pre-1970 VW Beetle 1200cc for these the quote was £1800, way below the rest at £3000
Adding experienced named drivers will again reduce the premium, as does adding a spouse, you may not have one of these, take my advice and keep it that way!!
If you complete the Pass Plus driving course you can reduce the quote even futher , in the Beetle quote it was reduced to £1500
The black box thing can be added and reduces the cost even further but lets you away with nothing! they will increase your premium if they see any signs of dodgy driving (apparently driving round a roundabout can be flagged up as dodgy driving) but as you said, they can't be fitted to the SJ or the Beetle (no electrics speedo)
The SJ, even the 1000cc 410 is group 6 insurance which is a killer for a first time driver trying to get a low quote,
As mentioned already, try the classic/agricultural/farming companies, you may get a good deal
You may have to get something else for a year or two until your no claims starts to kick in...
When i had a company car I insured a Citroen 2CV for 6 years that wasnt even on the road, just to build up my no claims bonus for when I eventually needed it.
Sad times indeed but too many young lads are now jumping into high powered motors and causing huge damage, and these compensation claims can be huge..
when I passed my test my first car was a 1300cc MK2 Escort with about 57 Bhp. I bet you'll struggle to find many cars under 100bhp now