And nothing says "could not cut it old school" like steroids, leave those for professional athletes.
I don't think using your mid/realcap m-mags will work, even if it did you would have so many bbs in the loading tube it would be weird. I plan to run with 7 std mags loaded to 50 bbs, 6 in pouches and one in the gun, assuming others are using realcap loadouts that is as many rounds as over 11 m-mags. I get mine off ebay from HK, I've heard that they are not importable but I order them one at a time so they get shipped in a padded envelopes. That way CBSA doesn't generally open them. It costs about half as much as if I ordered them in country so even if half got seized I would come out on par. I am so far 3 for 3 success rate. Not that I would ever suggest to try and cheat CBSA or anything.