First, thanks to SCCutler for the kind words! I've had a conversation with Kyle, the stuff below is just general info about the way I would approach a task like this.
To go from Hagerstown to San Diego area, I'd recommend heading for El Paso, TX, and crossing the high plains (mesa?) between ELP and TUS at 10 or 12000. I've taken that route many times and found it much more comfortable than trying to cross the higher mountains to the north, and it doesn't add much to the overall flight length/time. And I recommend timing it so that you overnight at ELP, and then get an early flight (oh-dark-thirty early) so that you're crossing the terrain before the solar energy starts making the air turbulent - the DA-40's a great airplane but the long wing from it's glider heritage makes for a platform that rolls a bit more in the bumps than most folks are used to. And if it has the KAP140 autopilot the rolls can be enough to disconnect it - an annoyance that doesn't happen with the GFC700.
The "iffy" parts are the fall weather between KHGR and KELP. That southern area around MO/AR/OK can have IFR weather that lasts for a couple of days. Not a problem if you and the plane are both IFR, but I spent an extra day once in Hot Springs because I was rated but the Symphony I was ferrying was not certified for IFR.
The DA40, with 39 gal of standard fuel, at 10 gph, means I'm landing every three hours or so. That makes for longer days due to the extra stops. It's about 15 hours of flight time on airways with no winds, so to me that's two full and one partial day of flying by the time it's all done. If you do it VFR, I'd give yourself five days of schedule and hope for weather that lets you complete the trip in three.
The way I work checkouts/ferries now that I'm a CFI is that if the insurance company wants a significant amount of instruction/supervision in the airplane (say 10 hours), then I'd recommend getting that done during the ferry. If they want less, (say 5 hours), then it's probably cheaper to do the training locally and take the airplane home solo. You only pay for five hours of the CFI time and the gas, and don't have lodging or return airfare or other expenses.
Best wishes,
