I've seen this said a few times now, and admittedly, I don't play with many other boxers out there, but I've never seen a boxer out there killing low levels, its more killing BiS gankers that think they are invincible.
@OP-Moving your team, five at a time, to the raid instance is the safest way as if it detects more than 5 accounts, over that limit will get kicked and it just doesn't work well for getting your intact team to the instance, it will disconnect at the worst time, so 5 at a time is the "quickest" way to try to raid. That is until one or more of your team is picked off and farmed so that you waste your time reviving and try to get your team together. Just a time sink that isn't worth doing. You could possibly move your team there one at a time, to avoid the farm... but again, HUGE time sink.
They want you to limit to 5 man teams, but not to cut off those donations entirely if you want to try and do those raids. It's a waste though, you'll spend more time trying to get your toons into the raid before they are farmed than raiding. And if you're thinking there aren't people to exact on you their small measure of "revenge" for being killed before, you're fooling yourself.
My suggestion, get a group of friends, or an open minded guild that wouldn't mind you taking in more than 1 toon, they do exist, although rarely, and stick to the 5, or just do heroics.
On reflection, if you do try this, come back here and let me know I was wrong, or at minimum, your experience doing it.