I started out backpack only. Learned after a year you cannot do that for very long. #1, only plan on doing 4k sq ft lawns or less. More than that, and you are doing way too much mixing and time wasting at a property. #2, a backpack will KILL your shoulders/back if done day in/day out.
I now backpack only the smallest of lawns and ride on the rest. Perhaps you want to look into one of those 12V push sprayers like TurfEx offers?
7x14 Stealth SE Enclosed with 48" side ramp
08 Toro Z400 48" deck, 21HP Kaw with EZ Vac twin bag
09 Exmark Turf Tracer HP 36"
21" Toro SR4 Super Recycler
Stihl KM90 Kombi w/ straight shaft trimmer & tiller heads
Husqvarna 125B Blower
Turfco XT5 Aerator
Turfco LS-22 Overseeder
I can do all things through Him who gives me strength.