You didn't mention in your original post whether you're planning to carry an iPhone or Android phone anyway. If so, then you've already got a GPS that will do what the DeLorme and Garmins will do -- excepting that the smart phones are not waterproof and will take more effort to manage the battery life. But for purposes of the maps and the gps related functions, the smart phones are great.
If you're not planning to carry a smartphone, then ignore the rest of this message.
If you've got a smart phone, then get the apps mentioned (PCTHYOH and Halfmile PCT are great, I haven't used Guthook). If you've got an iPhone, then Gaia will let you carry the USGS and NPS (and other map sources) for the whole route, together with your waypoints and tracks. And Maplets will be useful too for USFS and NPS and many other maps. I'm not sure about mapping apps for the Android, but I have heard that Backcountry Navigator is better than Gaia on the Android platform.
If you're using an iPhone and have not already read the article about battery drain management, be sure to study it carefully:
I don't know of a comparable article for the Android phones, but if you hear of one please PM me so I can add a link to it in the iPhone article.
I can only speak for the iPhone, since that's what I use. Depending on the model (4 or 5) and carrier (ATT or Verizon), and depending on how much I use the camera and other apps, I'm getting 3 to 8 days of backcountry use on one charge. I'm getting one full recharge plus a little extra from the Jackery Mini 2600mAh battery 2.7 oz). YMWV.
For waterproofing, the LifeProof case works AOK and is light and has a slim form factor.
Good luck, Amy