Most of the “ improved rear pedals” threads are focused on the breaks.
For your consideration, as great as the 8 is for the front seat pilot, the back seat is very compromised for “full control”.
It the goal is for the back seat to be able “ take control” for basic maneuvering, intro flights , take the plane while the front seat eats, the 8 does quite well without rudder input, and the back seat can meet the bar without the stock or other rear pedals.
If you want the rear seat to be competent for acrobatics , you will need not only pedal ( stock or other) but the rear throttle quadrant will need to be optimized , and then there is rear seat instruments.
Getting competent braking for rear seat is the challenge and requires significant fabrication for a solution that would be trustworthy for landing.
So, if your mission is to allow the back seat to take over for a period of time in the air, no aerobatic, or landing , the stock rear pedals are not required, and the addition space both for you and the rear passenger will be more appreciated.
If you are thinking of an 8 capable of training from the rear, it’s more than just rudder pedal solution.
Jw