How about just MGComics? I'd find that easier to remember than your current one, and it contains all the relevant info. Easy to read, easy to write.
ScampiCub has been a handle of mine for about 13 years now since the cringey deviantArt days. I kept it purely out of habit (and because my little sister liked it) but it has no meaning at all. it's easy to remember and I suppose that's all that matters. For anything important (business related, like Patreon of Ko-Fi) I use my real name. Most people online know me as Kate.
Slinger would make a fine username but it's ALWAYS taken. KJSlinger is fine too, but by now ScampiCub has stuck so, wevs.
I agree, though, some nicknames sound a bit unprofessional. Then again, 99% of people in and outside the industry understand we need to go with a more unusual tag sometimes, especially if your name is common. I see plenty of professionals with jokey nicknames. Just avoid anything outrageous and offensive and it won't be a big deal.