I'm actually gonna disagree a little bit with the bros here.
No matter how careful you do it there is still the risk of sh*t getting into the syringe while packaging it.
Why not just pin before leaving?
Just practice your normal hygiene habits while traveling and you'll be fine. Hell, I stabbed myself earlier this morning and more than 1000 miles from home, and I'm fine, uh, I think.
Preloading syringes is perfectly fine and it's an accepted medical practice as well. As an extra precaution, I always put preloaded syringes in a seal zip lock bag since I tend to pack them with my toiletries.