I hadn't thought of it in that application. The 3rd Arkansas was almost always posted to the left of the 1st Texas. As you know the guide of the brigade would normally be to the right and therefore the "dress" would have normally been toward the 5th Texas Inf. That would have put the 3rd Ark at the far end of the brigade battleline.
The exception to this would have been Gettysburg where the 3rd was ordered to keep contact with the Emmitsburg road. this should have made the guide to the left and therefore the 3rd Arkansas should have been the lead regiment. But they were also ordered to maintain contact with the Texas regiments to their right which were ordered to keep contact with the left flank of Laws Brigade.
As we know now from the reports Hood appearently had issued Law orders to skirt to the right to attack Little Round Top directly because they could see the Union fortifing that position as they advanced. That is why the 3rd Ark and 1st Texas wound up fighting by themselves at Devils Den for over and hour without support against at least 8 Union regiments.
Again here as you said, the 3rd Arkansas, not knowing the brigade had split in two and not being supported on their left flank did exactly as you said and fought hard to protect their, and the brigades, exposed flank from enemy fire from the Wheatfield. While at the same time supporting the 1st Texas against the enemy on the ridge to their front and Devils Den.