Your budget is always key to what you buy for equipment. Many of us start with used things. Especially true if you “don’t really know much” about driving things. You haven’t handled many brands of harness or vehicles to have preferences yet. Seen many of styles, designs in harness fit that have been developed in even the last few years. Most harness makers will make custom sizes for the same price as their average shelf sizes.
At five, your mini is almost mature, but not “developed” yet in muscling with work. So she might start in one size harness, change enough in a year of work to need a different fitting harness. So buying a more expensive, name-brand harness should probably wait a while. Synthetics are easy care, well fitting in many cases. Nothing like the $79, bad fiting, nylon strap harness in catalogs.
I see LOTS of used mini harness on Facebook driving sites, in all styles and sizes, for relatively low costs. It is a good place to shop if you ask good questions of the sellers, look at good photos of the items. And you can post to ask for items, giving sizes, price you want to pay. Some maker names are great at fitting minis, others are not.
You need to get her measurements before shopping, head, girth, back length, rump, chest. Mouth width.
Has she ever seen a dentist? Minis can appear fine but have LOTS of problems with crooked teeth, too many teeth, because teeth don’t shrink along with the rest of their body! Teeth can stay horse size in the little skull, out of alignment, need removal, to make fitting a bit very difficult. Just bringing this up because bitting issues with minis are so common. Some never have any issues!! You won’t know until she is looked at. But teeth problems often cause other problems, so knowing what you are dealing with makes problem solving easier. At five, her mouth should be almost mature, no new teeth coming in.
At this point, getting her a bridle without blinkers and bit that fits comfortably is your lesson starting point. You will want a bridlepath trimmed in the mane so bridle sits snug against her skull and top of neck. This may need weekly trimming if she has the typical thick mane! You NEVER want a loose fitting bridle, too easy for it to come off. When hitched, that can cause a wreck!!
A surcingle really just needs to carry the long lines, so “cobbling” one up is not difficult. The professionally made ones have lots of rings, but most go unused. Things to avoid are small rings that reins can’t slide thru fast and easily. Even with a twist in it, rein needs to slide thru ring when pulled or released. Rings on her barrel sides will be most used, to keep her between the lines, not able to turn like when lines are along her spine. They can just turn in a heartbeat, tangle. Reins down along sides controls both ends of equine!
Comfy Fit harness does a lot of mini harness in synthetic material. I would look for a used surcingle or check their cost for a new one to order. Should get a crupper with it to keep things in place, help her get used to the feel before she wears a full harness. They also carry an assortment of mini size bits too.
Warm the crupper with your hands BEFORE putting it under her tail. Horses get upset, react poorly until that cold crupper warms up!! Not nice seeing a 16H+ horse try to sit down on you!! We learned warm crupper means a happier horse! Ha ha
Get a nice lightweight whip to carry during her lessons. Needs some length so you can reach her out on a circle or during ground driving. Witmer Coach Shop in PA, sells inexpensive, lightweight, driving whips in all lengths of stick. You can add some parachute cord to get long length you need. Lunge whips you find locally are too heavy, lash never reaches the horse when needed, hard to carry for the whole lesson. The lighter whips are much nicer to use, easier on your wrists!
My first thought with new drivers is to stay simple, not invest much until you see if your animal will drive. Most minis are very cooperative about driving, which can be tricky. Owners may not practice each step enough to have mini be solid, before moving to the next step. So mini does not understand well enough not to react badly when surprised later. The “Oh look! I trained him to drIve in 30 days. We are doing a parade next week.” Sometimes it works, usually there is a big problem when mini gets scared. You CANNOT muscle them into obedience, you are seldom as strong as a frightened mini.
Your driving groom experience has probably taught you a lot, not trying to talk down here. Just passing on what I see happen a lot with minis. They get underestimated with cuteness factor, not considered “real horses” to need full training time, because they are so accepting of new things.
Welcome to the Group! Please do share stories and photos with us as you progress in her training.
And there are a few minis who WON’T drive, not ever, safely. Don’t have the mind for it.