Help with overheating 4.2td gu dual cab

[Fakeofergbo]

Hi guys been on the forum for a while but first time starting a thread.

I have a 1999, GU 4.2TD Dual Cab and i am having trouble with it overheating (or at least the temp gauge on the dash climbing) all the time. I live in Canberra so it is probably cold for about 8 months of the year so i dont have to worry about it but nows the time when i start to have some trouble

First things first im a carpenter and i tow about 2 tonnes of trailer to work everyday plus the dual cab has a steel tray with a fairly basic aluminum canopy. went camping on the weekend had 3 bloked and a moderate amount of gear on but not too much and it started to overheat going up the clyde mountain and i was in second doing about 50 stuck behind a horse float, when i got to the top i took the spotties off and had no problems on the way home. a couple of pics below



car modifications to date are to do with engine are

brand New radiator this time last year i removed a pwr triple core aluminum one
winch
tjm bullbar
spotties which i have removed to try to get more air flow
denco water to air intercooler
imatation safari snorkel with standard air box
it has dual batteries under the bonnet
running 265/75/r16 maxxis bighorns
3 inch straight through exhaust
vdo boost and egt gauges
running about 9 pound boost
egt gauge seems to run about 250 degrees normally but when im heading up hills or pushing it itll run up to 550 max

its been fine all winter but now that its starting to climb to the 28-35 degree mark my troubles have begun again. just after some advice/ maybe people that have had the same or similar problems and what they did to fix it?

things i have thought have that might help include,

maybe custom airbox and 3 inch snorkel to get it to breathe better?
changing the denco front mount intercooler to a top mount (maybe a cross country for example)
installing a thermo fan in front of the radiator
new turbo?

could there be a problem with my thermostat?
apart from that im out of ideas as im certianly no mechanic