Don't get hung up about hi viz or a hat. If the twat who's driving isn't looking you could have a luminous iron man suit ,and it wont save you.
I find something with a bit of reflective material in it works, along with some half decent lights.
Layering is the key. Bibs for me, sportful or castelli,look in the sales. Merino long sleeve base layer, with a long sleeved jersey over. Windproof gilet over that
packable rain jacket in back pocket, cycling cap under helmet. i sometime use a buff if it's very cold, tremendously versatile piece of kit.. I wear a pair of winter boots(north wave Fahrenheit) with merino socks. Winter gloves. a good tip with the gloves is to buy some liner gloves to go under them, mountain warehouse do some nice one for about a fiver IIRC.
This might be a bit controversial, but most of my winter kit is black, or predominantly so, with reflective accent on the bits that move, arms, legs etc.
I've been a wildfowler all my life, and its movement that gets you seen generally, and solid blocks of colour( and black is a colour

)
Thats just my opinion, and others may vary.
