Would only standalone rifle plates be usable for shoothouses

On the fence if this belongs here or in tactical gear - my apologies if this is in the wrong spot.

Would using exclusively NIJ L4 SA rifle plates be considered sufficient for use in shoothouses for attending classes, or would I be expected to buy a IIIA carrier or plate backers for use under?
Would I still be happier for the duration of the shoots run go ahead and run a low vis IIIA carrier anyway, and keep the plate carrier and rifle plates elsewhere, or is that alone justification to just get a solution like the Mayflower PC that can be reduced visibility or carry both?

NIJ Level 3 SA plates would be sufficient if you’re attending a carbine class. Obviously the protection would be limited to areas covered by just the plates. If you’re attending a pistol class then soft armor, either a concealable vest or integrated with your carrier would offer more protection.

The Mayflower Lo Profile Armor Carrier would give you a modular armor carrier that would provide soft armor coverage and allow you to upgrade to plates if you needed to. The QD connectors for their chest rigs is also very well thought out.