Well it does say tools, so you could interpret a vehicle as a tool... Just depends on how much you want penalize someone for playing a troll or dwarf and how much you want to hamper your team by having one in the team. Using the rule to the nth degree means you can't use each others guns, commlinks, vehicles, scuba gear, or anything else that would or should need to be modified without penalties.
Never, ever, EVER,
EVER touch a man's tools without permission!!! (ok, professional rant over)
Ever thought about how much lung capacity a troll has/needs to remain conscious??? Or what a mask meant for the head of a 10 foot tall person would look like??
In 'reality' they couldn't wear a human scuba mask cause the sides would sit right ON their eyes!! Ever gone to the department store and tried to put on clothing from the 'age 3-6' racks??? Yea, not comfortable. (don't ask)
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In the end, it boils down to how much realism you actually want in your game. If you are looking for lots of realism, clothing, weapon, tool, gear sizing does matter. If you are glossing over the details and just playing for fun, then don't bother with any of the sizing issues...
I bother with it simply cause it has the added effect of cutting out some twink builds (body 15 str 10, 22/20 armor trolls...) simply cause they usually can't afford ALL the toys with size customization on them...
..... And it leads to some rather funny situations.... Like when the troll rigger was KO'd and the 2 dwarves had to figure out how they were going to drive the Van (troll sized) away from the blood bath the run turned into!