He was within "reaching distance" of the passenger compartment when arrested though, one prong of par. VI at my post 17.
Wow your a lot of help , everyone seems to forget that there must be probable cause for any action. The officer can't just keep digging in hopes he may find something he must have probable cause. If this probable cause turns something up that deems further search or arrest then fine but he Must have cause first. To many people are giving police way more power than the actually have.
Assuming arguendo it was indeed a valid "search incident to arrest", NO probable cause is needed to search, that is just one exception to the warrant requirement.