just wanted to add my experience!
my big sis works with me, and as she waxes, and i do st tropez, we've had a coupla go's with combining the two!
personally i would tan after waxing, cos i know that my skin isnt particularly sensitive, and as long as the skin doesnt seem to have reacted post-wax, thenn i'd go for it!
the only prob you might find, is that the tan can go on a little patchy, as waxing seems to act like an EXTREME exfoliation... taking of layers of skin in some areas (often delicate bikini / underarm areas) this isnt always apparent until after you've done the tan (as i found out last week... white 'pits for a few days!!!!!)
not much help i know...
best bet?? i reckon buy some st tropez mousse / spray and latex gloves and 'do' yourself at the last possible moment,then you can also touch-up any areas that need re-doing!
hth x