This is one of the bummers about the galley/living room slides. Some coaches have them start a little further back but most squeeze tall drivers.
Re: comfort, you could replace the seat with a better quality unit or have a good upholsterer add some thin High Density foam to the existing or replace it with either a medium or high density foam on the seat and back and then re-attach the cover. This would only run about $150-$200 while a new seat is at least $800...plus you need to get it to match the co-pilots seat...
Re: the distance to the dash versus the slide in the back feeling, what I have found (6' tall...and shrinking) is that I pull the seat forward a bit and lean the back further to the rear. I then fully telescope OUT my steering column and tilt the wheel back further. It resembles a car more than you would think re: the ergonomics and is comfortable enough for 300-400 mile stretches...but you should be taking breaks about every 200 miles or so for your safety...and for more coffee.