Remeber always go one size down from your tent. So if you got a 4x4 tent get the 3x3 flood tray. https://www.amazon.com/dp/B00CJIANQW/ref=cm_sw_r_other_apa_kl7tAb3P4N0N5
To rise them off the floor use baking racks, or this flood tray has groves so the pots sits above the water. You can also put a thin piece of wood under the tray in the back so all the water goes to the front.
I got the tray at a local hydroponics store but this is essentially the same thing
https://www.amazon.com/Botanicare-Tray-3-3-Feet-Black/dp/B00CJIANQW