The lootfilter addon is good for auto-deleting all gray items. If you set it to delete white, remember to add "cloth" to the keep list, or silk and mageweave cloth will be deleted too. I boost with a 70 mage, too, and I usually only loot when my main is drinking or if I will break the instance reset limit timers. Boosting 2 groups of lowbies simlutaneously, I have over 2000 pieces of silk cloth, around 100 green items that I haven't de'd (100s more that I have). I leveled enchanting on one of the lowbies so I can DE all the BOP blues I got in there I already had to make a bank to hold just silk, and when I hit Strat, I plan on creating a new alt called "runeclothbank"