Good on you!
Yes you can get more with a horse in harness.
But as Alexia pointed out. It is a HUGE learning curve from riding to driving so please find a mentor to help you.
(Hubby grew up doing this and has two broken backs to show for it)
We get all our
firewood with our work horses.
But another option for your saddle horse is to drag logs from the horn.
Dally only do not tie hard and fast!
That way if your horses put up too much of a protest, you just let go of the rope.
Have fun!