Looking to get into heavy hauling

I live in south central PA and am looking for some advice as to what equipment to purchase. I have been pulling flatbeds and step decks for 15 years and am looking to get into heavy hauling. I have been asking around and have been told many different things as to what to look for in equipment. First off, I have been told by many to get a Rgn stretch if I can afford one and if I can't get as close to a 30ft we'll as I can find. Also, I've been told to go with at least three axles, some are telling me get a 4th flip or a booster. Next, some say get a drop side for the lower deck height and others say a flat deck with no more than 20in ride height. I figure I live in a decent area to haul equipment, Got Volvo, JLG, Cleveland Brothers in Murrysville, Annville, And Letterkenny. Also there are two places that make tanks, steel tanks west of me and fiberglass tanks east of me.
I have my own authority also, so guys told me they bid jobs by the hour and others by the mile. Those that bid by the hour said base your time on an average of 45mph. What's the best way and about how much do you charge on an average load? I know a lot depends on how wide high and heavy a load is.
Lastly, I was told to steer towards new or newer equipment with very little use. Quite a few guys told me be very careful of used equipment. Heavy hauling is very strenuous on equipment. Also, most everyone said get some type of sleeper on the truck even if it's a small one.
Thanks

Looking to get into heavy hauling