A Beau VI in March 43 would most likely be painted in Temperate Sea Scheme. Extra Dark Sea Grey, Dark Slate Grey, Sky under. One single, large letter on the side, if anything. This would most likely be in red, possibly Light Slate Grey. Serial would be Light Slate Grey or black, IIRC.
I find it unlikely that it carried full WR-codes at this time, but have been proven wrong on many other occasions.
Typical '42-'43 livery:
Kyrre