155 bow front?
It is my understanding that the cortez ray (rays in general) require a long tank for swimming. Like 6 feet or longer. I see in your original post that you are planning to rehome your tangs, are you planning to rehome the ray too eventually? A young ray might be okay to start in a 155 bow, but with five tangs in there as well that tank is going to be cramped. I assume you will have live rock for the tangs to hid in and around. That too will take up space that rays like to hide in the sand. That is just my opinion. I know that this warning comes up all the time for tangs and large breed fish in small(ish) aquariums, so I am sure you already know what I have said, but I just wanted to make sure that you have considered the stress you will be putting on the tank inhabitants. No judgement here though, I think everyone in this hobby has over loaded a tank at least once.
As far as mixing tangs with rays; I have never owned ray, but I have seen them in tanks with tangs and never noticed a quarrel going on. There is always that chance I guess, especially if they are all living closely together and already stressed. If anything, I would say it is the other way around as rays are known to eat small fish.
Hopefullly a ray expert can help you better with this. Good luck!