White sweater (bonus if you have a cycling jacket or safety vest), skate shoes or sandals, and dress pants.
Seriously though, some people don't like people having no camo but IMO we should slightly move away from that and make some of the regular skirmish days more relaxed in rule format in regards to what to wear (milsims should still have strict requirements though but for regular skirmish days IMO whatever you have is good enough). For camo depending on where you live Gorilla Surplus on East Broadway in Vancouver, Daves Army Surplus (DSTactical) in New West, or PoCo surplus (in PoCo obviously and another branch in Langley) will have cheap OD combats for you most likely.
Anyways, I suggest some old raggedy clothes you don't care for too much preferably in a dark but NOT black colour, believe it or not but black actually stands out quite significantly (try it one day and see for yourself especially try it at night, you won't believe it till you see it), navy blue or a dark bluish purple is actually best.
As for footwear, at minimum those hiking cross trainer
things but better to have proper hiking boots
(you probably have hiking boots, and if not I'm surprised since there's so many nice trails nearby Vancouver like the Baden Powell and West Coast Trail)
Gloves if you have some, preferably "low profile" and form fitting. Grab a pair of dark coloured work gloves from home depot or rona (I use a pair of "Watson" gloves
for biking) this is to prevent lots of pain from finger shots in case you're unlucky and get one in the hand.
A mask you can probably rent from panther for $5-10 for the day or w/e but I'm not so sure about Big Foot, best to ask around and see if another player has any. Are you on the Op-For or BCAC forums? Ask there and you'll probably be able to borrow from someone who has an extra mask.
EDIT: Also this is something I picked up on but CADPAT works better in west coast environments than MARPAT because of the green "mossy" trunks we have on the west while MARPAT is better in prairie and badland environments since the trunks of the trees are "dead" and more brown.