I just discovered (yesterday) that mine looks to have the bypass. It's under my lower bunk. Remove the mattress and then the plywood board.
Here's a blurry shot that shows what looks like a bypass valve at the bottom:
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-Scott, DW, DG, DB, and DD
2011 Passport 2590BH
2009 Ford F150 SuperCrew F
X4 5.4L w/Max Tow