Ideas for how to hide an 8ft sewer vent pole in backyard
There a few ideas out there. Not sure what your exactly looking for. 

Best I could come up with is...

Hide the sewer vent post with a custom built wooden or metal slip-over post with a solar light. (Light post) Although you would probably have to add a vent. 


Finish it off with a wooden planter box over the man-hole.