A stationary spray rig with a working hose was not uncommon in another time. Sure it had wheels, but the idea was for the hose to be uncoiled to work on an area. They were known as estate sprayers. A concept that I do not consider obsolete. In another thread we are discussing liquid fertilization. That is something best done through an estate sprayer due to the increased volume required for safety to the grass. How big a lawn are you working on? I normally want 1 gallon per 1000 sq ft or else 1 gallon applied in 2 different directions if more volume is needed.
Compressed air and vessels under pressure are something I respect. Unless the container is pressure rated to begin with like a stainless steel soda fountain keg, I would not put something under pressure. I think it is safer to withdraw liquid from a tank and use a pump to get it through hose. 1/4 hose can be used, however, there will be pressure loss that increases the more volume you want to discharge at. I use 300 ft of 3/8" hose on a commerical spray rig and use a regulator at the hand piece to reduce 400 PSI down to 40 PSI for the Teejet nozzle and spray gun.