You could apply an overall yellow filter mixed up pretty much as you have described, or, as an alternative or in addition, you could also use some oil dot modulation with Yellow Ocher oil paint.
The first would make a more or less uniform change in the tint of the base color and the second would create some variety between local areas of the base.
You could also use Raw Sienna as an oil dot modulation color which will give the underlying base color a darker yellowish brown tint.
Other oil colors, such as white, burnt sienna, and a blue, could also be used to add variety and highlights and shadows. The white would give some spots a faded and dusty look. Burnt Sienna would add a warm rusty tint, and a blue (Ultra Marine or Prussian, as examples) would darken and add a greenish tint.
(Blues are VERY powerful over yellow, though, so care and a light touch should be used until you're confident of the results you're achieving.)
FWIW, I usually start with a very light dark yellow base coat so that the later layers of finish and weathering will not result in a final look that's too dark. I think your base coat looks about right for my style of finishing.
For any oil dot color modulation you might try, unless you already have an established technique, I suggest that you pre-wet the area with clean mineral spirits before adding the oil dots and that you work with a single color at a time rather than add all of the selected oil colors at once. Both of these techniques will give more control to gradually impart the modulated colors.
HTH,
