Outer Limits 4x4 Board

Hi all, I drive a 1990 NG Pajero Turbo Diesel. I am planning an outback trip to 5 states including the Flinders and Gammon Ranges (SA) which can get pretty rocky. Over the weekend, I was 4WDing in the Bunyip State Forest on Melbourne's outskirts. Overall I am not dissatified with the NG's offroad abilities, however with the 31" Cooper STT's that I have, my car's underbody was scraping over the wheel ruts in some areas (obviously most of the vehicles previously using this muddy track were fitted with 35's or something) . Now my 4WD is a little rough on idle since that trip (I will inspect and repair any damage over the weekend). If I am heading to some rough places in the outback, should I be thinking of getting some extra protection underneath my car? Where is a good place to get it from in Melbourne? How much does it cost? Which parts should I focus on protecting? Thanks for any advice you give me, Sam

are you any good with a welder and grinder?

just be careful of the dry spinafex crap getting stuck up there and causing a fire.

skid plates over gbox/transfer and diffs if IFS would not be bad idea.

the front whould already have 2 decent plates to protect it.

hey mate, this is what i fabbed up for a mates paj years ago
it just goes under the transfer