Sky, nice rig. Here's a quick & dirty template overlay.
I didn't aim for perfect just good enough for first pass side check. Suggestions to consider:
* Reverse roof AC front to rear. I suspect flow will reattach then for sure - if it's not already. (I'm planning the same mod to
my rig once I get a round tuit.)
* Move hitch as far forward on truck as possible. A slider mechanism can retain low-speed tight maneuvers when needed.
* I agree a cab roof deflector could help a little. (Mine would also be a solar panel, ideally.)
* A vertical divider over the pin on the loft nose can reduce gap cross flow in cross winds. (My front-mount generator doubles for that purpose.)
Your loft nose is already raked, rounded on top, and somewhat convex side to side, so I don't see huge room for improvement there. If the side edge radii are less than 10% of the trailer width then per Waters 1969 (
ref. p259 fig. 4.128) those might be increased with nose work. OTOH aiming for clean side wash is complicated by awning rails, for example, so I wouldn't focus much up front.
Another RV benefit of an overhanging rear boattail is awning over the rear window. Ideally, the top part could be a solar panel.
PS- That custom box is neat!