Hi Nick, and welcome to the forum. You ask,
P.S.: If you know any reliable local guides with good English skills please share.
I know several here in Ubud that are truly the best and know all of Bali very well. Normally when doing a "road trip" you need not worry about paying much if anything for a room for a driver as they will most likely have a friend or relative in the area with whom they can spend the night. If not, then many hotels will provide drivers with a "driver's room" for no charge.
The drivers I know and work with do NOT participate in any sort of commission arrangement like many drivers who will take you to places where you can buy things...and they will earn anywhere from 20 to 40% commission on what you end up buying.
No question. For getting out and seeing the "real Bali" a professional Balinese driver with his own vehicle (Kijangs being the most popular) is the only way to go. If you come with an International drivers license, you can rent a Kijang and drive yourself, but you'll get lost a lot (which can be fun too), not enjoy the views, (never take your eyes off the road), and if involved in an accident, you will be at fault, even if you weren't.