I'm a engineer that has done many cost analysis. If the system to save gas/money is say over a $100 the payback is so far out that it usually is not cost effective unless you drive a lot more than the normal RV'er.
Even the $10 I spent my ram air has a 3000 mile breakeven. And a $360 "chip" will take 22K miles to breakeven before you start saving.
Drive slower, hold your foot steady, get rid of weight.
But then doing the project for fun maybe the point....
2015 Fleetwood Discovery 40E on a Freightliner XCS chassis with a Cummins ISL9 pulling 1 and/or 2 motorcycles, '07 Honda Accord OR a 17' Runabout Boat.