I'm chasing a set of bash plates for the triton and came across www.boosbashplates.com.au. They are dirt cheap when compared to the others. I know they arent 4mm in SS but is there any reason to choose that over 3mm given most of my 4wding is coastal stuff.

No.

of course avoiding the need for a bash plate is best.

Lift kits help raise the belly of IFS Utes.

Or just get a live axle 4WD. Problem solved. After 15 years of Utes I got sick of going katink and got a Patrol. Off road beast.