Being a sniper is, for me, a state of mind, rather than a look or even your equipment. You want to use what'll do the job...and in airsoft, it is usually to take out as many OP-FOR as possible until they get you. Because there is so little difference in range between decent AEGs and most dedicated rifles, compared with real steel, whilst stealth helps, you're usually close enough to be located eventually...
Browning M2's with scopes on...to handguns with optics...all have been used by snipers to achieve this aim.
I say, do what you plan to do, and most importantly, enjoy it and learn from failures and successes.