Just an observation following the discussion here...
Many a thread on the equipment forums (or "fora" if you prefer) goes into a big discussion about the limitations due to diffraction at f8 (or even 5.6!) and beyond.
Go over to the image forums where people are just concerned with images, and you will find hundreds of stunning images shot at f11 or even f13, with the DOF extending throughout the image, and no one takes any notice of such limitations!
So, my humble advice is, if you cannot focus stack a landscape for any reason (time, need for tripod, distaste for the process, whatever) and you have enough light, just stop down to get the DOF you want and get the image. Yes, if you blow up to 200% on your monitor and pixel peep, you will see diffraction effects. Though there is some loss of information, a bit of judicious sharpening goes a long way to making the final image look fabulous.
If you like large DOF landscapes, just shoot with the aperture you need, and adjust your PP as needed. Most high-quality lenses these days will be barely distinguishable in resolution at small apertures (there might be some differences in contrast). Yes, it's fun to know about and discuss technique, but never let worries about diffraction get in the way of making an image - it almost never matters in the end!
(Postscript: if your final product is an actual print, a factor that is not widely appreciated is that ink spreading in the paper is actually the final resolution limit, not the lens or sensor: I have found in my experience that the spreading of the ink in most photo papers has the equivalent of the effect of diffraction of f/10 or thereabouts for a 17x22 inch print. If you like printing on something like Velvet Fine Art it's even larger.)