The A321LR will not carry 200 pax (20t) and fuel for 3 ACT´s. You will have to reduce either the fuel or the payload. A lot depends on the actual OEW of the operator. Is it bare bones? With limited catering? or is it J and Y? I am not sure Primera Air will carry regular J (lie flat) seats. Perhaps similar to US domestic first class. There is not enough real estate for 16 lie-flats and 182Y. So your hypothetical config will probably be either payload limited or fuel limited. If you choose the 20t payload, the range will probably be right around 3000nm (+resereves).
The optimum configuration will probably be 2 ACT´s, and around 180 pax. It will take a premium heavy and high yielding (not LCC) route to optimise for 3 ACT´s and around 160 seats to reach maximum range.