Enclosed Trailer Skin Removal

[HB Lawn]

Ok, I have this 16 ft enclosed trailer that I need to remove the skin off the back ramp door, but I can't find the right Torx screw driver and bit to fit the screw heads. I tried a number T15, just a little too small and a T20 is way to big. So I think I need a T16, but i can't find one anywhere. Can someone point me in the right direction to find this special driver. Or if you have a trick up your sleeve, let me know.

Thanks
HB Lawn