If your route has areas where you'll be driving at 50 mph or so, grille blocking would probably help. Every time I've tried it, there's been a significant improvement (like 2 mpg). Definitely get a ScanGauge, or something that shows you what kind of results your getting from your different ideas you try.
When I tried to P&G or hold a good BSFC load going up a hill in my Jimmy with auto trans, I couldn't do it - mashing the throttle enough to get the engine load up there would always cause it to downshift & also shoot up right past my best fuel economy speed. So I found that just trying to hold it at best fuel economy speed did the best.
And 50 mph might be too high for your car. I was assuming it would be around 50 mph for my Jimmy - that lower speeds might be "lugging" it. But nope, turns out 40 mph was actually the best speed. (and I checked it a couple times to make sure). Too slow for the freeway (I tried it & got honked at a lot
), so then I found NON-freeway routes where the speed limit was closer to 40. With the ScanGauge, I found that coasting up to stops from half a block away in neutral really boosted the average mpg, too. It was weird getting used to acceleraing off a green light & then throwing it into neutral and coasting before even getting up to the speed limit, but if you see the light 3/4 of a block ahead turn yellow, that's what you do - and it works!!!
But do a grille block - that should help a lot.