MV's rig is mighty fancy!
I put my meadowbrook in the back of the pick up and borrow my Mom's 2 horse bumper pull,
My trailer is a 3 horse slant and the horse and cart might fit, but my trailer doesn't have an escape door in the first stall so I don't want to "trap" my horse in the first stall, In an emergency it would take about 20 min to get to the horse. And Pilgrim takes up two stalls.
Idealy I am looking for a 2 + 1 trailer, or a 4 horse slant, with an escape door in the first stall.
I know several people that a 3 horse slant will work for them, They have a smaller horse and/or cart and an escape door.
I have seen people put brackets on the back of the trailer to put the cart there, but I wouldn't do that with out an emergency exit, lots of people do , but personally I would not. I do think brackets would work if you had an escape door though.
The best time to plant a tree was 20 years ago, the second best time is today.