Headspace

Last year I made 70 gals of blackberry wine and it took forever to to rack it, backweeten etc. So this year I bought a wine pump. I plan to rack the wine from the carboys into two 30 gal trash can clean the carboys and re-rack back into them. My question is do I have to worry about headspace as the wine will be exposed for such a short time, or do I buy a bottle of CO2 to put a blanket over the wine while in the trashcan.

Thanks for any help..

Sorry about the multiable post I thought I was being disconnected...