I went with Ventura rack with two 51 liter bags. Nothing touches the paint and I remove it, store the bags and rack until the next long trip. I had a bagster tank bag with this set up and had plenty of room.
Packing tip.
rain covers are fine but a hassle to install and carry for a long trip when space is a premium.
I took advice from another rider with many years of long touring rides.
Pack your clothes and any thing you want to keep dry in small kitchen size trash can liners. Double them up and use the extra for dirty clothes.
Another thing, take clothes you are about to throw out. Socks, underwear, old t shirts, some of the stuff on the "gotta throw away soon" list.
Throw them away on the trip so you don't haul dirty worthless clothes back home. This makes room for the new souvenir t-shirts you may purchase on the trip.
Sounds a little radical to some but most men wear there undies far past their usable life span....

Must be a guy thing...
When you get home get new undies or if you run out buy new on the road.
One other thing on the soft luggage.
If it touches the paint, it will dull the finish.
Cover the painted areas with painters tape and take the rest of the roll with you in case you need to remove the luggage and tape for the photo shoot day.
Reapply the tape for the trip home and your paint will look like it did before you left.
If you want to spend the money, 3M makes a clear protective film.