Originally Posted by Hopper5000
even if you rack carefully there will still be oxygen in the carboy.
You're talking about oxygen being in the secondary right? I gather mostly all of the 02 has left the primary after 2-4 weeks of fermenting, conditioning, and being covered with an airlock as well as a dense 2 gallons worth of C02 blanket of in his 6 gallon primary. Just wanted to clarify this for anyone who might be confused.
C02 is much heavier than Air and O2. So if you do your best to cover the carboy opening when racking, then oxygen exposure should be inconsequential for up to an hour, possibly more... and still some of that C02 will push to the secondary with the secondary opening also covered as much as it can be during racking, and more C02 created by racking on top of the dryhops. If the OP gives this 7-10 days in the secondary, I doubt he will have oxygenation issues. Even with 1 gal headspace, most of which will be taken up by the 3.5 oz. dryhops, which expand when wet.