I managed to pull this one off through some improvisation along the way...

I realized I need to get myself some stiff brushes to spread stiff paint around... at least at the early stage. Right now I favour cheap beveled nylon watercolor brushes. Although the surface is not as textured throughout as I anticipated, it does have that beaten look, which I like! I need to get used to applying thick paint and letting it sit there untouched...
One thing I realized is that there is an advantage in using gloss acrylic gel for brighter colors. Matte gel whitens colors a little. In the end, I can always go for a satin (waxy) finish as usual.
In retrospect, there was nothing wrong in dealing with textures separately from the painting process: I won an honorable mention with such a painting. I'm basically making an attempt to do both at the same time, as most conventional painters do! As usual, my focus on results will lead me to use all methods concurrently... sort of my "anything goes if results are there" kind of philosophy!