I re-read the post I referenced above, there seemed to be 2 issues: (1) the small exhausts (2@3" on the originals) and poor ventilation in the firebox. The exhaust issue was handled with a mod to add a single 5" (good) or 6" (better) in the RF position; the poor ventilation issue was handled with a grate in the firebox to raise the fire and get 2"-3" of ventilation under it. From your pics, you might already have a larger exhaust.
Don't get discouraged, you still have a quality cooker. I think they reversed the normal layout and put the firebox in the bow so they could add that trick grill in the stern. Personally, I like the versatility they offer, just need to work on getting the air flow right.
Finally, don't underestimate the importance of Bludawg's comments: at least at start up having a head-up or head-down attitude can really hurt/help getting a RF stickburner drawing properly-EXPERIMENT!
Best of luck, looking forward to seeing some good cooks in the future!
Weber 26.75 OTG w/CI grates & SJ/WSM Mini
Home built 24"x72" reverse flow stick burner trailer with 18"x44" grill w/CI grates and upright SS gas oven/smoker.
Home built 48" fire pit with a 30"x30" Santa Maria style ranch grill.
Home built lump charcoal retort, iGrill & a bunch of other cooking toys.