Take a look at how Republicans in the US have gerrymandered their way to a House majority in the US elections and you will understand that this can still be done.
Of course, you might end up with seemingly random and disconnected neighbourhoods enjoined together to form a SMC / GRC. Imagine parts with Tampines enjoined with parts of Boon Lay and parts of Ang Mo Kio...
the US district boundaries are full of snake lines. think octopus lines might be more appropriate for some districts. the lines are drawn with devious precision, to guarantee that each party always remains in control of particular districts. absolutely brilliant works.
the Marine Parade legendary snake line is nothing compared to the US octopus districts.