I've used 3 ton jack stand pairs for similarly weighted vehicles many times, no issues (RX350, MDX, RDX ...) Jack in addition not required though not a bad idea for additional safety.
3 ton jack stand pair means each stand is rated for 1.5 tons for a total of 3 tons.
When using jack stand in pairs, part of the vehicle weight is on the remaining 2 wheels on the floor so not all of the 2.3 tons is on jack stands, maybe 2 tons at most? You need 2 pairs (4 stands) to get the entire car off the floor, which you would would 6 tons total at that point.
Invest in a good jack stand pair, not all are created equal.
Jack on level floor is optimum, but sloped driveway can work if done properly, use common sense.
