Roof tents on a Gen 3 ?

Has anyone any experience of mounting a roof tent onto a Gen 3 ? I'm planning a couple of long trips ( not quite "expeditions" ) and am looking at the Tentbox options particularly. I'd welcome any advice please.
I'm also particularly concerned re the recommended roof load capacity, which my manual says is only 30 kg ( !!! ??? ), that'd make even the lightest roof tent ( 50 kg ish ) impossible !!

PS Is the roof load capacity significantly greater on the Gen 4 because I've seen plenty of youtube overlanders with Gen 4 roof tents ?

30 kg is correct. For both. I have cross bars instead of the factory rails bolted directly to the roof and whilst doubtless capable of taking the weight I am still limited by the factory limit because over that and the police and insurance are not going to be happy if something untoward happened. The other issue is I have a roof box and it costs me something like 4mpg. Also also on my farm I have over loaded the roof as needs must and it has a very dramatic effect on the stability, I wouldn't like it on the road, far too wobbly.

Member 'Reason 2 Doubt' (aka Stuart) had a roof mounted tent on his Jimny, he took it on a long trip from the UK to Italy, see the photos here

www.lines-associates.com/piwigo/index.php?/category/677

Unfortunately Stuart sold his Jimny earlier this year, so he might not be on the forum now, but if you look at the photos you might get an idea of what he did and the following post has a few more details.

www.bigjimny.com/index.php/forum/6-jimny...tent?start=12#226831

I'm frankly astonished by the 30 kg limit, all roof racks would be more than that before you put anything on them !!
Are we saying that most people ignore the weight limit then, because Reason2Doubt's tent and rack would be way over the limit as would all these youtube overlanders ?

The Jimny itself can take the weight and more when stationary. It is the dynamic load when you get moving is the limiting factor. 

Also just because lots of people are fitting them doesn't make it right. I think I worked it out for the Gen4 with the Front Runner full roof rack you could the only strap a 5kg load to it, as that weighs about 25kg.

The real issue is if you happen to roll it on the road, your insurance will be void.

As long as you know the limitations/risks/possible consequences, it is your choice at the end of the day.