I am very lucky that I have direct hacking to off road hacking, but still wouldn't dream of hacking without hi viz on myself or my pony - for one thing, it makes you visible to air rescue team should the worst happen but also allows cyclists, dog walkers, runners etc to spot us too. I am one of the few people from my yard to year hi viz and often get comments such as 'your bright' or 'we could see you coming' ... Which is the whole point! Funny enough, those that don't wear it are the first to complain that someone didn't see them!
I always wear - a hat band, hi viz coat, gilet or tabard depending on time of year and hi viz gloves.
Pony years - hi viz noseband cover, rein slips, neck band, high viz saddlecloth, tail guard and leg wraps.
All in various colours - pink, orange and yellow.
IMHO everyone should wear high viz whatever time of day or year or weather conditions regardless if they are hacking on roads or not.