Many club shoots allow lee way in the rules. New shooters are allowed to shoot first match even if they don't have a "IDPA legal" holster. Mesh vest are considered concealment, I even scored as a guy kept telling the SO he couldn't seem to turn off his LASER sight. I guess removing the batteries was beyond his expertise.
I am one of the minority of shooters who simply switch mags to carry ammo and leaves the range carrying the same equipment I shot the match withI do this also, as others at our club, even though there are to be no loaded guns other than on the COF. No ammunition in the safe gun handling area.