Well, being so early in the fight the tank would for the most part be clean. I would just do some light wethering to show some light use. As the days went on the tank would get dirtier and so on, providing it wasn't lost in action.

They would just be covered in a light coat of dust.  Most of the Stuarts that first landed on Gudalcanal were knock out within the first month.  Being lightly armored and with no room to maneuver most were sitting ducks if they got away from their infantry support.

Yeah, maybe put some sand on the running gear and around the fenders? 

Those tracks were babied the whole trip across the Pacific.

Guadalcanal was a Big Deal , and all hands knew it.  So, they'd probably looked newer than from the factory. 

Probably all kinds of ecess grease on the tracks and the running gear.  There would have been little extraneous gear on them, and everything The Book said to stow aboard would have been in place, shipshape and Bristol fashion.  All of the markings would have been by-the-book, too.

this may scan odd, but, when crossing the Pacific at 10 knots (240nm/dy) there's a lot of time to fill, and a lot of people to keep occupied in that "inbetween."

'42 was  still a time when the Services still had a lot of inertia from the interwar years, before the expediency of winning the war took hold.  This self same thinking is also why most of the Stuarts were lost, too.

So, day One (D-0 or D+1) they are probably just dusty, no real wear at all; not even that many scrapes or dings, as they would have still been following feild exercise habits , like not busting trhough foilage, but using existing roads and paths.

Oh, and all tools would have been Sergeant-level painted to spec, too.  Metalwork might have been semi-gloss, but it would have all been painted.  No bare wood handles; no hardware stores on the ships, either.

Those Stuart's may have been exposed to salt water getting ashore, or manuvouring about to get into position.  Do you know how they were landed: by landing craft probably as there is no deep water portage at the "Canal?"  Salt water leaves white residue, and will quickly lead to rust and chipped paint.  The extra Preventative Maintaince mentioned as part of the sea passage may have lead to dust and sand building up in lubicated locations orf the running gear and tracks.  Do you have any photos of these tanks, as black and white can still show the locatojns of wear and tear even if yu cannot decipher the colors and causes.  Good luck.

Do not get all hung up in the chipping and extreme weathering phase currently all the rage in armor modeling. 

US Olive Drab paint was known for it's durability and weather resistance throughout the war.  

Armored vehicles in WW II mostly didn't last long enough to get extremely weathered before being knocked out.

Even in the harsh North African climate you'll see photos of Panzer III's and IV's knocked out without a chip on them. 

Marcus McBean

They would just be covered in a light coat of dust.  Most of the Stuarts that first landed on Gudalcanal were knock out within the first month.  Being lightly armored and with no room to maneuver most were sitting ducks if they got away from their infantry support.

 

The Japanese has minimal AT weaponry for the opening of the battle there.  And the Marines were pretty good at their tank/infantry co ordination. Read up on the Battle of Tenaru River/Alligator Creek, the tanks M3 and M2, were instrumental at mopping up the remnants of the Ichiki Detacment the morning after the heavy fighting at night. Most of those that were knocked out by the Japanese fell later during the Bloody Ridge battle well after the landings. 

And I agree about the chipping, avoid that fad. Tanks and other military vehicles get filthy as soon as they get into action. But chipping not so much. It’s “artistic” as opposed to “realistic”.

These tanks were basically brand new, so there was no major rust, and would have very slight use chipping to the tank's openings.  The M-2A4's were from 18-27 months old.  The M-3's were from 4-17 months old.  The most iconic Marine M-3 tank, MC301, was probably accepted for service by the USA in May 1942, and subsequently given to the Marines.