I had my local Kydex guy make a few holsters for my Sig since the tall sights won't fit my leather ones anymore. We decided to try to make one that would carry the can attached. What we came up with is a front break holster that is tight on the trigger guard and allows the weapon to slide in from the top and out the front. It looks like it will work, the draw is fast with a little practice.
He is doing Glocks next.
Here are some photos.
You might want to consider putting a break a way from strap for the break front holster.
I made one for my Beretta M9 with AWC Hush Puppy suppressor. The M9 loaded is heavier than your SIG and I found that I had to make the holster tighter around the trigger guard...which caused some finish wear.
I tried again and lined the holster with some silcone suede and riveted a thumb break front strap to keep it closed. It worked well and kept the finish wear to a minimum.
I wish I still had it.
PS how doe you like your suppressed P228?
A buddy of mine is a NCIS agent and he has a SIG factory long barrel with a AAC 9mm Evo suppressor on it. He is ok with it but does not like the finish wear on the outer tube.