I think Craig makes some great points. My questions to you would be, what conditions will you be shooting under? What apertures do you intend to shoot at and will you have a tripod?
As an owner of too many lenses, I recently made an exhaustive comparison of the 16-35 gmii, 24-105f4, 28-60 plastic kit lens, 40 2.5, 40 1.2 Voight, 28-75 Tamron G2, 85 1.8, Tamron 28-200 and 70-200 gmii.
Here's what I found out - at f/8 to f/11 they are all really close. Shockingly close raw. With a little correction (applying the lens profiles) they are really hard to decipher even at 200%. These were brick wall tests for whatever that is worth. At f/8 & f/11, the 28-200 at 200 with lens profile corrections was shockingly close to the 70-200 gmii center to edges. I know, there's some purple fringing on the 28-200 but that is so easily corrected.
There is no doubt that the fast lenses are IQ engineered to excel at larger apertures. However, f8 becomes an equalizer and the size and weight (and cost) of the "fast lenses" has a negative ROI at F8-F11. In fact, I am now looking into sunstar rendering more and more because the lenses are so close at landscape apertures.
My feeling after the tests was that the 16-35 gmii I own is exceptional and I would not think twice about using it for 2.8 and beyond throughout its entire zoom range - all the way to 35. The 24-105 is weaker than the 28-75g2 until f/8 where they meet (along with most other lenses). The 28-60 is my "pocket lens" that I carry with me when I am out with long teles just in case I see something. It's as light as a 1.4tc. I rarely use the 40 1.2, but when I do it's at f2 or wider.
I cannot get my mind around 1.4 lenses for landscape use unless its astro landscape. F8 and be there still holds true.
If you don't mind switching lenses, I don't know why you need to add to your kit. If you want to limit switches and plan to shoot mostly daytime and landscapes and only want to carry 2 lenses, I guess the 20-70 would work. I had the 20-70 but sold it because I always ended up bringing the 16-35 gmii and using it to 35 anyway, so a wide (20-24) midrange zoom wasn't as necessary. I also felt the 20-70 looked flat, which is a subjective thing. I never felt it had depth. I probably didn't give it enough chance. It was plenty sharp.
If, after the testing, I wanted to go super-light and was taking mostly daylight or tripod landscapes, 16-35 and 28-200. At f8-f11 it's not enough IQ difference with A7RV for me to carry the 24-105, 28-75 or 70-200.
If it's a car trip where weight isn't an issue and I don't mind changing lenses, i'd bring 16-35, 28-75 and 70-200gmii with tcs. I think you have everything already, but if you want 2 lenses, add the 20-70.