ACTIVE implement guidance would involve a hyd hitch that goes side to side to keep the tractor and seeder in line. 


PASSIVE (autotrac) implement guidance just needs the proper activation/subscription on the screen and receiver on the implement. I'd go this route, cheaper and easier and still does well. 

You don't need another RTK receiver, a basic SF1 on the implement can share RTK off your cab receiver. So it's cheaper than you think or maybe you have an SF1 3000 laying around for tillage etc. That will work and RTK will share back to it.