I would stay away from anything textured right now, anything with malasses with only cause teeth issues down the road.
You can continue feeding what you are now but I really recommend Safe Choice, I swear by the stuff! I have feed it to fat and skinny, young and old, gotten the outcomes I wanted.
Feeding 1 scoop twice a day should do the trick, along with the hay of course. It also would not hurt to bump him up on the amount of hay, I would change to something like coastal and give a bail a day. Its horse nature to constantly graze, so getting a slow feeder hay net and bumping up the amount of hay would also help.
The Junior feed by purina is almost the same feed as the safe choice by nutrena, only difference is safe choice is higher in crude fat. SafeChoice Horse Feed by Nutrena Purina Horse Feeds - EQUINE FAMILY