Just drill a tunnel to the Mediterranean.
It’s been 5 million years since that dried up.
You probably knew this, but there are two different proposals for linking the Dead Sea with the rest of the world’s seas.
The Red-Dead canal would run the length of the Israeli-Jordanian border and bring water from the Gulf of Aqaba to the Dead Sea basin (a section of tunnel would be necesssary), using the fall to generate electrical power. As the Dead Sea filled back up, the surface would spread out and salt levels would drop, and eventually the evaporation would maintain the water level without having to stop the flow from outside.
The Med-Dead idea would work the same (and would be a shorter route; a section tunnel would still be required) and would be entirely under Israeli control.
Having a moat along the Jordanian border doesn’t sound like a bad idea, but I’d favor the Med-Dead canal version — with the canal being about 200 feet deep, and flowing along the border between Gaza and Egypt (buh-bye tunnels) and Israel and Egypt.
Not so easy. There is a couple thousand feet elev change to get over from the rift zone to the coast.