if you wanna do this in a save area there is no problem. And can be great :-) but if you wanna use this for training i mean preparing to carriage driving then i would say use a good bridle and dont worry to much about the AND way.
that mean not that you have to push and pull and so on. Even driving can carefull and give the horse enough space to move their heads. If you look to Simon for example, His obahma is driving with a rope halter, tho he is learning him now with a Cook bridle.
Because he knows that you can do some bit more finetuning if needed.
But still then the horse have plenty of space to be himself.
i am driving almost every day and the pony never complained about the less of room for his head or that it is too strong / hard for him.
And yes he will when he doesn't like it. and i accept that, he know that for sure.
I know that because when he is not in the mood he can walk away from the beginning and we wont go driving.
Or when i ask a trot and he will stay in walk even after several questioning then we stay in walk. He have a reason for that i think.
So he get the freedom to do so. Most of the time later on he ask if he may go harder. and i say yes when it is save enough.
So both are happy then, it think
why would a good bridle reduce the happyness of a horse?
i think if you are realy good you can do long reining with nothing. it is then no longer reining but stearing your horse from behind
or am i wrong??