You might want to try highlighting the sights with something like nail polish, just something maybe with a little contrast, that you can get a quick and decent alignment with, and just "shoot through" the suppressor.
I have standard three dot night sights on my Glocks and my suppressor blocks the sights when its on the gun. I just use the dots for alignment. It works on the same principle as the old OEG type sights. You shoot both eyes open, your strong eye sees the sights, your weak eye the target, and your brain does the rest. Once you get used to it, I think you'd be surprised at how well it works. I can make consistent head shots with mine at 25 yards shooting that way, and up closer, its very precise.
The dots make things a little easier, as they give both horizontal and vertical alignment, but with say with a white rear, and an orange front, something you cn see against the back of the can, you should be able to get a decent traditional sight picture and see through the can.