Commercially I am not sure it is viable. After all who is going to see the sponsors logo as you pelt round the countryside? At a point to point, team chase or three day event you have thousands of spectators, an announcer who mentions the team or horse name when a sponsor includes their product (i.e Everest Milton or Relentless Fight the Ban) and press coverage afterwards.
Hunting has the foot followers who won't even buy a raffle ticket let alone an expensive product advertised on your arse let alone get close enough to the action to be able to read your sponsored saddle cloth and breeches!
That is before you even get to what a master would think of someone turning up dressed like a point to point jockey with sponsored breeches and coat...
You could if you had a silly company who didn't want any commercial value to their sponsorship.
Horse boxes and trailers with logos wouldn't be seen very much as parking is often out the way of the public.
You can't exactly have saddlecloths and embroidered jackets on the hunting field and there is no commentary where sponsor notes can be included.
So realistically no unless you can write a very persuasive letter in how you could actually provide anything beneficial to a company.