That Ron’s harness looks fantastic for the price!
When I first started driving, the woman who got me started said that green horses and drivers should always start in leather harness because it will break more reliably in the event of a wreck. The same individual is famous for wrecking so take it for what its worth :lol:
For just working in the long lines, I agree, you really don’t need a harness. Even for the purposes of teaching your horse to accept breeching and a crupper, you can cobble those things together with inexpensive parts.
The first harness I bought was used. It was a nice Smuckers harness, but a miserable fit for my horse, and I didn’t even realize at first how badly it fit. It was fine for long lining, but the minute I tried to use it to hitch it just wasn’t working out. I tried looking into replacing parts to make it work, but I could see it becoming an expensive and frustrating endeavor.
I luckily found a second used leather harness that was an ideal fit, and even then I had to do some parts swapping. Fortunately the maker was still active and replacement parts were readily available.
For several reasons, after gaining confidence driving, I was in the market for a synthetic harness and decided to go brand new. It was a dream working with one person, receiving the harness, fitting it, sending back parts that didn’t fit properly, getting replacements, etc. etc. The entire harness matches and is in good shape.
Well, I went around my ass to scratch my ear, but the short version is:
In my experience, horses - even of similar heights - can have vastly different body dimensions and shapes. Harness frequently requires a bit of fitting and having to swap out parts is not uncommon (my 14.3h morgan needs a cob sized harness, horse sized girth, horse sized turnback, pony sized cavesson, etc. etc.).
If you have the time and patience, you can get a very nice used harness and make it work, just be prepared for the potential of hunting up replacement parts.
Otherwise, consider purchasing an inexpensive (but not junk!) newer harness where you can work back and forth with the seller until the fit is just right. It really does make life easier, especially if you have a horse with oddly sized body parts, like mine. 