AAAAwwwww - you've missed all the pics and discussions!!
Here's a few - the smallest pony I've used for "work" is 35" at the withers - so maybe only 2" taller than yours. I don't have any pics of her actually "working" yet. The largest so far is 43" at the withers and she works with a 40" mare.
2012 & 2013 we had limbs come down from a couple of trees and then we also had a tree service come in and "drop" 3 trees, but not remove them. The ponies and I spent lots of time pulling "parts" of trees -some just wee little branches and some quite large. Some were pulled by single ponies and some by pairs. The bonfires we had after each series of "pulling sessions" and photo taking - WERE AWESOME!!
Here is a pair
a single mare pulling 2 - 32 gallon trashcans w/ manure back to the manure pile. She is actually wearing a homemade breast collar made from a western "string" pony girth, not a collar and hames. I think Stuffy is 37" tall.
my girlfriends' pair pulling a home made chain link drag with a pony sized Pioneer forecart.
and again pulling a disk
And Bit "working" single.
If it will let me load one more - here is the pic of the girls' moving a round bale. This was the first time they'd pulled as a pair with their new harness on.
All of the work we did could easily be done with a tractor (we don't own one). In most instances, it could have been loaded into a trailer and pulled by the lawn mower or into the back of a truck - but some I couldn't have budged by myself. My truck couldn't get any purchase on the ground above to pull that bale - the girls got this one into the paddock for me (the 2nd one they couldn't). The last bale was too wet and stayed in place for over a year until I had a friend move some hay for us - he moved that bale into our bonfire pile to burn. Working with the ponies this way is sometimes more work - but that is the whole intent. To get the ponies trained, to enjoy working "behind" them and to get moving myself while using less mechanical means....