Mr Cheese 123,
Why not order online from the USA (all the brands you mentioned) and have it sent out to HK? This is what my friend does and I was surprised to hear the savings that she made compared to HK shopping not to mention this will solve your problem on getting the right sizes.
She told me this today. One orders online (US website) they delivery to a courier company in the US, courier company delivers to you in HK or Mainland.
Update~!!!
The outlet store that I mentioned previously with the Levis, Lees, Chevignon and other brand name Jeans does NOT carry sizes above 38W. I was in the area and checked it out.
I was told however, for those interested in getting US sized clothing, or plus size or "Big&tall" to travel down to Tsim Sha Tsui. There are Export Outlet stores located all long Carnavon Road. (Exit D from the MTR).
Also, correction on a store name: "Uno ono" is wrong...the name was actually "Uno NUO" *sigh* I knew it was Uno something. :P
How do I find the "Big and Tall" store in Tsuen Wan?
I can't exactly tell you because I have no idea what the street name is, and it is not near the MTR. But I did come across another one by Sham Shui Po MTR near the Golden Computer Centre. You get off exit D2, go left, and there is a clothing store called XXL Collections.
Try Citygate Mall in Tung Chung on your day off. I find bigger sizes in stores like Nautica and Timberland. Also found jeans @ Lucky Brand Jeans. Good luck!