Introductions discussion

Hello everyone, I am a solo submissive guy from Australia (and fairly active in my local kink scene as well as on FetLife), with an ongoing desire to stay locked up. I have been reading here for some time, but lately I decided to take the plunge and sign up after the site upgrade mainly for two reasons:

• Google search results were broken, and I suspected it might be because I wasn’t a member (it turns out that wasn’t why:p)
• I was looking to get some guidance from the more seasoned members here. Sorry if this isn’t the right sub-forum for my question (I couldn’t decide whether this belonged in the Devices section or if it was fine posting it here): I’ve been “experimenting” with locking up intermittently for a couple of years: initially trying out a CB-2000 (not much luck; I thought the rings were too large) and recently starting to use some models from DHGate (I realize they are lower quality, but I didn’t want to spend big on a premium device until I knew if I’d like it). Although I enjoy the sensation of being in chastity (which is hard for me since I self-lock, and I’m not prepared yet to try mailing the keys away due to issues described below), I keep getting chafed raw under my shaft and - with my newest device, which has one of those cylindrical hinged rings but I liked how it looked - on my scrotal sac where it rubs against the ring. From what I can gather, here is what happens: when aroused, I swell up and push against the cage, pulling it downwards. I am using 50mm rings because the next size down for most of these devices is 46 mm, and trying one of those hurt too much. However, this seems a little large so my scrotal sac gets pulled into the ring as the cage moves away from me, causing the underside of my shaft to rub against the bottom bars of the cage. When I go soft again, the sac and shaft get rubbed back. Is there anything I can try or do about this? (I’m currently figuring out whether lining the ring with rubber or something similar will help keep it in place by reducing its diameter.) Am I right that if I end up getting a custom-fitted cage from someone like Mature Metal these issues should decrease because the cage would fit me better and therefore a) the ring would be tighter and move less and b) the cage itself would be tighter to stop me growing initially? Thanks in advance for your help and advice, hijk