Hello Brandon:
As others have said, "Congratulations & Welcome."
Personally, I wouldn't extend the filler across the width of the truck. I see a couple of potential problems:
1. If your driver's side fill isn't considerably higher than the OEM filler on the DEF tank (see #2) you could have some low spots that might hold DEF. Our experience with our 2014 FG suggests that some of the trucks (at least ours!) have extremely finicky sets of sensors that may be sent over the deep end if they get crystallized or "out of bounds concentration" DEF in the system. I'd be afraid that a long run of hose with low spots could send those sensors into a tizzy. We've dealt with sensor "tizzies" more often than I'd like to admit and our current successful strategy has been to keep them comfortable, feed them only the best, etc. However, others here have had no problems at all. Hopefully your truck will be one of those.
2. If your driver's side fill is considerably higher so that there are no low spots and the fluid runs smoothly and rapidly into the tank I think you will overfill the tank frequently. One of the sensor interactions that caused a tizzy for our system was an over fill condition. The system apparently monitors the level an doesn't like to be below a certain level, nor above a certain level.
We have a fairly simple set up that works well for us. We purchased the 2.5 gallon boxes a couple of times and we saved the hose funnels from those boxes. Those hose funnels also thread onto the 1 gallon jugs which we prefer to use (they store better for us). We try to let our tank get down to where it will take 2 gallons (we have our sight tube marked at the full, one gallon down and two gallons down levels). When we're two gallons down (usually about 100 miles after three of the level lights go out) we put in two gallons from two separate jugs using the hose funnel. When done we rinse the hose funnel in water and store it for the next time. We're getting about 450 - 500 miles per gallon or 900 - 1000 miles per filling. So while this process occurs more frequently that I'd like, it isn't something we have to do every day.
Good luck!
Howard