I found my ome kit in the gq a bit harsh on the road.
But it took everything with ease..
And they lasted well..
8 years I had the gq for and still going strong when I recently sold it..
Imo..
I'd fit a softer set of springs to suit your everyday driving.
Then if needed (the T Vans ain't that heavy..) fit some in spring air bags to assist the extra towing weight..

Now bracing is a good insurance..
I personally never did but it was always on my mind when doing big trips and the old Q looking like something from National Lampoon Vacation..........

As darren has pointed out there are 2 main options both with pros and cons..

The Boss kit (first shown) is a great simple easy kit to fit but imo isn't as good as the superior kit.
My reason is simple.
The Boss kit still applies 100% of the load to the one area.
Where as the superior kit spreads the load over a few square feet area of chassis either side..
It braces to both chassis cross members either side..
But as darren said have a read, there is heaps of info and quite a few members running each setup here..

Cheers