Right I agree with Masonic, you best bet so you do not have to worry about it at all is to inject your weekly dose the day of your flight. If you are inj 2x a week I would presume you are running longer estered cmpds. If this is the case, pinning once a week is not out of the question. You may have to split the volume in half and inj in one glute and the remaining portion into the other for example, just so you don't blow the site.
If you must fly with it, be careful as they are illegal substances so just by chance you could wind up in trouble. I like the idea of the shaker bottle and bubble wrap. That sounds like the best method to me, may have to try that sometime...