The only issue you will have is the size of the person riding with you, how experienced they are
and how experienced you are.
My son has been riding mini-bikes and mini-cycles since he was 8. He's 14 now. Up to the point he hit the last growth spert, the bike didn't know he was there. Only knew it at stop lights where you could feel that it was a bit more top heavy. He is the best rider I've ever had on the back. Experience pays.
The bike did the hills here on the east side of PA with no problems.
BUT..... He is now almost 15, 180 lbs, 5'9" and a High School Freshman football lineman. Needless to say, my 5'10" and his 5'9" made riding two-up too uncomfortable for us (picture those pict's of loaded to the gills bikes in Asia). He fit's on the fixer Sportster
. But it's way more top heavy at lights.