Put in a roundabout connecting Kuhio Hwy, Kapa'a Bypass Rd, and Papaloa Rd. Make Aleka Lp right turn only at Coconut Marketplace and connect Aleka LP to Papaloa Rd. Buy out the Shell station and make Haleileo Rd and Papaloa Rd a four-way intersection at the stop light.
These would combine to alleviate the traffic jumping Coconut Marketplace and reentering to use Papaloa Road southbound in the afternoons.

Kawaihau & the Hwy - great place for a roundabout.

How about one way north - that's two lanes from Coconut Marketplace end of bypass road (gets rid of a multitude of issues including easing traffic through downtown, plus we don't have to build more in that direction), with bypass road south toward Kuhio Hwy by Coconut Marketplace - easy to continue on highway. The north end of the bypass road could be built out better/wider, etc, with the two lane end made into two lanes toward Coconut Marketplace. For those don't want as would have to go a few blocks back or whatever, how long do you sit in traffic now that doesn't move, where yes, you may drive a little longer to go around - yet if traffic is moving, you likely will be there quicker during those tied up times of day. This could all be done using the existing highway and most of the existing bypass road (the 2 lane part), saving a mega-ton of dollars, and in place quickly. We literally can move traffic along much better with the resources we already have.  Plus by adding a lane to the one lane part of the bypass road will make a difference as well, all going in one direction, toward Wailua.