I too will be adding planer boards to the arsenal this year and have been studying all winter. I attended 2 of the LOTSA walleye seminars provided by charter captains, 1 in Erie and the other in Buffalo.
One of the common practices by both was the use of lead core. Both used a system of Mono backer, a length of lead core then another length of mono or Fluorocarbon leader. Also a small inline swivel out on the end.

Thought i would pass along, hope it helps.