(maybe this should be part of the "anatomically correct" series. If so, feel free to edit accordingly, as I don't know how to add it to that list)
Could a roughly human sized, human weight, bipedal, anthropomorphized flying squirrel achieve significant gliding capabilities?
Details, limitations, clarifications, etc:
With the understanding that lower weight makes flight/gliding easier, they can be slightly shorter than humans, on average, and more slender as well, but I want to stay away from avian hollow bone structures and similar non-mammalian adaptations. More slender bones, like bats, are acceptable. Because I suspect someone will ask for specific numbers, let's say the average height for an adult male is 5' (1.524 meters), and an adult female averages 4'8" (1.32 Meters). The lower end of "normal" BMI for a 5' human male is just under 100 pounds (45.3 kg), so lets make that the upper end of a normal healthy weight for a healthy specimen of this species, bordering on overweight.
While the overall body plan should be humanoid, adjustments can be made to limb length, if it's aerodynamically required to achieve gliding capability. But the (hind) legs should not be any longer, proportional to the rest of the body, than an actual human's legs, so they should only be shortened, if needed, not lengthened. And the arms (forelegs) should not be any shorter, proportional to the rest of the body, than an actual human's arms, so they should only be lengthened, if needed, not shortened. Also, the arms can be as long as, but not longer than, the legs. Summary: legs can be shortened, arms can be lengthened, but only if needed for aerodynamic purposes, otherwise they should stay as close to human proportions as possible.
Gliding should be accomplished by with the aid of a patagium, a parachute-like membrane that stretches from wrist to ankle. No third set of appendages/wings/etc., and no massive re-imagining of the two existing sets of limbs outside of what an actual flying squirrel has (neither set can be converted to wings, or any similarly drastic change). The patagium should be mostly collapsible/fold-able/retractable/etc. to achieve a "mostly human shape" when it's not in use, just as an actual flying squirrel can achieve a "mostly squirrel shape".
Tail should not be longer than about 3' (1 meter).
Should be capable of an average glide ration of 2 (that's 2 feet of horizontal distance traveled for each 1 foot of elevation lost)
The setting is Earth. No exotic gravity, atmosphere, etc.
Disregard evolutionary improbabilities. Assume the evolution is/was possible, however likely or unlikely it might be. In other words, it is outside the scope of this question to declare implausibility due to evolutionary restrictions.
Are there any known aspects of real-world biology that prohibit such a creature from existing? If so, what are they? If not, what is the most likely form this creature would take within these parameters?