Good question.
First of all, stationary bypass is only allowed as a result of stopping during the movement phase. I've looked and can't find a rule permitting vehicular setup in bypass.
In addition to that, given that the opponent is allowed to check for clearance using the (haha) method of holding a unit counter vertically, one can't assume that bypass movement would be permitted to have allowed entry to the position in the first place (even though it may be obvious, there is no rule that states 'players can setup in obviously clear bypass locations').
I've looked for some errata on this, and can't find anything permitting setup in bypass. Therefore, I think the rule for stationary bypass is applicable D2.34
Which is interesting because I know I've setup in bypass and allowed opponents to do so, it seems like it would be a good/obvious idea. So I might have missed something, I didn't do comprehensive research, just looked in the most likely places for this information.
To your question, the rules specify placing ? counter 'in' concealment terrain at setup. For obvious reasons, bypass CAFP can't be in concealment terrain unless, for example, the odd case there is inherent terrain, like orchards, in the same location as a bypassable obstacle. The bypass unit does not 'appear' to be in open ground, it IS in open ground.
2.34 STATIONARY BYPASS: Unlike Infantry, a vehicle may voluntarily end its MPh using Bypass. It remains straddled across the hexside last traversed, with the CAFP defining its position within the hex, its VCA, and its vehicular Target Facing. Its ability to change its VCA is limited as per