George, to add 5 minutes to your mix time you are going to want to start with colder water/maybe ice so that your finished dough temp is the same. Hobarts heat up the dough a lot. Another great option is to use the same mix time but add in some stretch and folds every 20 minutes after mixing until the dough feels nice and strong. Of course you will have to drop down the yeast a bit since typically you are going right into the fridge, and now you are spending more time at room temp before going in. The perfect amount of yeast will have to be found with experimentation, but I would start by decreasing by 15%.
A finished dough temp of 70-78 is a very wide range, Regardless of what flour you use I think you should hone that in to within 2-3 degrees max. This will improve the predictability of your fermentation.
Also, if you are comparing bromated all trumps to sir galahad, that is going to give you a different product regardless of mix time. All trumps is very high gluten (plus bromate makes it act even higher) while sir galahad is an all purpose flour. With similar hydrations I doubt you could ever get the strength and ability to trap gas (or puff) from galahad that you can achieve with bromated all trumps, but you might prefer the tenderness of the galahad. You might have better luck comparing King Arthur sir lancelot flour to all trumps since they are in a similar protein range.
Another thing that would help you to get your galahad closer to all trumps performance is balling later (doing bulk rise then form balls closer to when the dough is being used).
Good luck!