I went out to some hives a few days ago. THe guy i went with got stung (bees got mad, figured out how to get up his pans). I think they will be able to sting you even with clothes on underneath. But if I wrong, someone correct me casue I dont have a lot of experience.

The issue for me is overheating. I wear only underwear under my suit. But then again, I'm also usually barefoot, so I do get some apitherapy on my toes.

For me, the purpose of the coveralls is to keep the propolis stains on one set of clothing... they never come clean. I get stung thru the suit, and sometimes bees climb up my legs. You should see me do the dance.

But the key is overheating ... in our recent 90°+ days, my suit is soaked with sweat and affords less protection against stings. But I can survive stings. I worry about heat stroke or heat exhaustion.

Clothing aint your problem. The suit is.

Suit needs to be bulky to help keep the bees stingers away from the skin. Which could you get stung through better, a spandex bodysuit, or a winter jacket? You need the bulk of a proper suit to keep the stingers away from the body.

Save your hide from stingers, and get a proper fitting suit.

Even with a "proper fitting suit" bees can sting through. Anytime you have the suit next to skin (belly, back if you're bent over, shoulder if you have something in the pocket, etc.) you can get stung. The bee suit typically gives the new beekeeper more confidence which keeps the bee keeper moving in gentle motions. Bees are more likely to sting if you move in jerky short movements. Bee suits keep your clothes clean. Many long time beekeepers will wear white coveralls (plain cotton ones) without gloves. Most will wear a helmet with veil, but not all.

Well, this ain't reassuring. I'm gonna write to the manufacturers of Kevlar and see if I can make me a proper stingproof beesuit.

If you're a beekeeper you're going to get stung. If you are new to it you can build up your immunity by using ice to numb an area (hand) and inducing a bee to sting it. Once you are up to several stings at a time your body start to ignore the venom and only the piercing stinger hurts.
I preferred to take benedryl after working the bees in the beginning. Work bees, get stung come home, take benedryl, take nap. Minimal swelling and the body got used to it. Spring time will cause a bit of swelling, but the body gets used to it quickly.
Beekeepers are usually immune, but if their wives wash their suits the wives become allergic. Theory is that the dried venom, aerosolized in small doses causes allergy. Wash your suit every chance and don't let your spouse do it. A suit that has alot of alarm phermone from stings will make bees alarmed and sting it (you) more.

Here is a link that might be useful: Virginia Country Life