Another view of harness 

Would it be better to get larger wheels or add a wedge on axle to lift seat? Does it make a difference? 

Balancing Miss M

I am trying to achieve balanced draft with both equines I drive. M, my 13.3 H haflinger mare, is put to a meadowbrook. I believe the cart is too low for her. If I lower the shaft loops it would drop the shaft some but I don't think this would be enough. I could either get larger wheels or add some kind of wedge to raise the seat. Would either be OK or is one preferable to the other?