I think the lack of Junk Rigs in the Proa world is due to the fact that those who build Proas are usually speed freaks, as such they assume that modern high performance rigs are the thing to use.........
Rob uses the very expensive Ballestron rig, other's use Bermuda Rigs, I feel that neither are for Proas since the Ballerstron is unstayed, putting huge loads onto the vaka and it's self...... Therefor costing an arm and a leg, and winning the heavy weight class of rigs, coming in first, as the heaviest.
The Bermuda? Expensive, one will need roller furling jibs front and back..... That alone is a huge expense, imagine shunting, rolling up one sail and unrolling the other..... Too much!
The Oceanic Lateen is the best rig for a proa, it's truly amazing! But it can't be reefed! The islanders never reefed, they had enough sea room to be able to get away without reefing. Oceanic Lateens belong in the Pacific.
I feel after years of rig research that the solution may be a modified JR that shunts easy, and most important reefs easy!
Here's a vid of me shunting a Junk Rig. Dead easy!!! Shunting is at 9 minutes, before that, in the video I explain the rigging details that make shunting possible......
All d best.
https://youtu.be/4qP7Jy8fqiA