Hello Max, I posted this message about a year ago but I think this will give you some options
If you have any wear then you may as well do the whole seat over that will be very expensive. You do have some savings in doing just the welt trim.
My guess is that you can buy new seats for a lower cost then doing the full reupholster on the 2 front seats if you do one then do both.
If you do the repair only the back will come off the unit assembly and the seat fabric can be taken off the seat it will then need to be cut apart the trim welt is between the seat top and the sides it's a job that can best be done in a auto trim shop.
I would guess $3-400. dollars/ seat and should be a 6-8 hour job.
FYI you can buy a new seat Flexsteel at Camperworld for $500-800
You may like to visit the flexsteel site here is a link they may have been the OEM doing the seats
http://www.flexsteel.com/vehicle-seating/products/motor-home-seating/bucket-seats