As much as I love the P51, if this involves a lower cost survivable ground attack aircraft there was none better than the A1E Skyraider.They did beyond excellent work in Korea and Nam and they have a big enough frame to carry any modern ordnance. Of course since few fighter jocks want to fly the Warthog, I doubt flying a re imagined Skyraider would be popular.
It has a loiter time of between 14 and 42 hours depending on your trade-off between ordinance and external fuel tanks (with no resulting pilot fatigue since the pilots can do shifts), costs a fraction of what a modern manned fighter does and can carry up to 3,000 pounds of ordinance.