What kind of weight are you hanging currently? If it’s 5 pounds or less, your wrapping and attachment technique needs improvement. If there’s no penile tissue bunched in front of the hanger insulating your glans, you’re definitely not using the right technique and putting those glans at big risk. I know Bib offers a free critique of your technique if you message him a bunch of pictures through his forum. SWM from MaleHanger is also helpful, I’ve heard.
Once you start getting up there in weight, I’m a firm believer that small head size, which also means lower overall flaccid size, can be an issue. I’m assuming your overall flaccid girth is in proportion with your flaccid head size? Whether your head is in fact “too small,” I don’t know because you haven’t offered measurements.
All that said, I always had problems with slippage when my flaccid was smaller. Years of hanging and other PE have given me a larger “walking-around” flaccid, which has helped immensely in the hanging department.
Even on days when it isn’t as prominent, I’ll get semi-erect before wrapping and hanging, to avoid pain in the glans from little or no “shoulders” for the hanger to grip onto. This goes around the most common advice you’ll hear, which recommends having no inkling of an erection while hanging. However, if you consider guys who don’t grow much at all during an erection (show-ers), they’re basically hanging with a semi erection already, right?
Note, I’m recommending “semi-erect” and not anything resembling hard. You’ll have to play around and figure out how to do this without getting a strong erection and get yourself wrapped and situated in the hanger safely. I’ve read plenty of other members who are growers more than show-ers recommending what I’m saying too (think maybe GPrent is one, but don’t quote me).
Do whatever is recommended elsewhere, but if you still get stumped, try experimented with plumping your penis up before clamping down the hanger. I’d only recommend this if you’re hanging more than 5 pounds though, as mentioned earlier: it’s such a small weight, you shouldn’t have slippage issues at such low poundages if you’re doing everything else right.