Tyre change for Clearance

[UncleD]

G'day all
I am looking for some specific information regarding improving my 2005 Hilux. We love the new Lux except for a couple of now well known shortcomings i.e. clearance and clearance!

The Lux is an SR Turbo diesel dual cab with Gitsham aluminium tray. I have had an aluminium mesh / canvas canopy made to suit with tool box and water tank slung under the tray behind the rear wheels. A toyota Bull bar is fitted (steel) so it always has some weight in it. I have fitted 'AirBag Man' airbags fitted to the rear to compensate for the sagging due to weight in the tray.

The majority of driving is dirt road or dunes with 5 of six trips to Adelaide (1600km round trip on bituman) per year.

The vehicle is fitted with Bridgestone Desert Dueler 9R15 on ROH Trak 2 steel rims. Although these have proven to be reasonable tyres they do nothing for the clearance issue (being 15 inch rims). I am up for new tyres in the next 6 months and want to know how to maximise clearnance with a new set. I am willing to go back to 16 inch rims and dont need any greater width in the tyre and the tread pattern of the duelers is quite aggressive enough for our uses.

The vehicle needs to retain much of its 'road manners' as it is our only vehicle.

My two questions are.
1. What would be the best changeover of tyres / rims to improve the clearnance issue? (This is a question of tyre/rim specifications rather than preferred brand however your suggestions are welcome). I have found tyre identification codes very confusing (especially with the variation in units; metric/imperial)

2. What modifications to the suspension are avilable to improve clearance without being too radical / messing up road handling? (I have seen the Snake Racing adverts for lift kits but at $3000+, I will make do with whatever improvement I can get from the tyres!). Are there less costly / radical lifts available?

Thanks for your advice.
UncleD