If everyone said "I don't believe in gender stereotypes" and actually practised what they preached, i.e. by dressing kids in anything regardless of some arbitrary label of "girls" or "boys", we wouldn't have this nonsense of people worrying in the first place.
I don't intend to dress any of my kids, boys or girls, in dresses or skirts because I don't personally like them. [Unless, that is, I happen to get the clothes as gifts.] But if, when they get old enough to choose, my boy chooses a skirt or a dress? Yeah, he's going to get to wear it. I wish more people would grasp that great opportunity before they get to school where they say they like things because they actually do, not because other people tell them they should.
What is the worst that people think is going to happen if you put a boy in pink or even, god forbid, a dress? Mocking and ridicule from others? Well, that's their own issues, not yours. People just rolling over and being a doormat saying "it's too hard to go against the tide" just makes it that much easier for the miserable people to carry on putting their own views onto others. I'm not saying put your boy in a dress if it's going to get him beaten up, but if the worst that will happen is a bit of teasing, I'd much rather teach my kid to cope with the teasing and that it's all nonsense than submit to it and go along with the teasers' views of what is 'right'.
And I say all this as someone who has been getting flack for being 'too masculine' since I was a kid. I've been sneered at and shoued at by my own father and I've lost count of the amount of times I've been called a dyke. But I don't give a toss because I prefer boxer shorts, short hair suits me more, and I refuse to live my life according to someone else's opinion.
Gets off soapbox Apologies in advance if this sounds ranty, but this is one of my pet hates, people saying they don't believe in following gender stereotypes and then doing exactly that.
OP: dress your kid in whatever servicable clothes you have to hand. If you bring him up with the same attitude you have [i.e. it's decent and a bit of pink will not turn him into a girl] he will realise long before he's an adult that his baby pictures are just cute baby pictures, and the clothes will merit nothing more than perhaps a giggle.