Everything you said is true, and I agree with Tedmond as well.
I've done many of the Elantra PTS, and I do find them to be one of the easier push-to-start cars. It's about the same amount of work as doing a regular-key car.
So, I don't want to discourage you, but I will agree and disagree with what you said at the same time.
Yes, I can do those cars in about an hour. My tool box is especially set up just for remote starters, so I have everything on hand. I know exactly how the car comes apart and goes together. I have some (but not all!) of the wiring locations and colors memorized.
Even if you've done stereos and lighting before, it'll still take you a little extra time to work out how the dash comes down, your back might not be as accustomed to kneeling and twisting as a daily installer's is, and you'll have to run back in the house a few times to get a tool you forgot you needed.
So that's the only warning I'd really want to say----budget a few hours just in case, and it's not a bad idea to have a second car on hand if you have to run out for last-minute supplies or tools. And where a regular installer can program the module to the car in moments, it'll take you a few minutes to carefully read through the instructions and watch what the lights are doing to make sure it's right.
Tips:
---The driver's underdash has two screws you can see, and two more you can't...they're on the side. Hmm, how to explain this in text? Sit in the driver's seat. Look at the left AC vent. Now, open the driver's door. Between the left AC vent and the door panel, is a sort of "sail panel" that sits on the side of the dash, and you can't see it unless the door is open. Make sense? OK, so you have to pry that off to expose the other two screws for the driver's underdash.
---To get to the kick panel to connect the ignition wires, uncrew and remove the hood-release handle. Pop up the front half of the door-sill plate. Peel back the door weatherstripping. Now, you'll see the top edge of the kick panel is held in by a little clip...reach in there with a hook tool and pry that out. Then bend the kick panel out a little more so you can look behind, and you'll see another plastic clip....get in there with a long screwdriver and pop that out.
The door sill and kick panel on these cars are both very fragile and crack easily. Run the car outside with the heat on maximum for a while, to soften the panels a bit.
---Above where the driver's left foot would be, are several factory harnesses with plenty of space in between them. I mount the remote starter brain here, with the wires coming from the brain pointing toward the back of the car. Take note that the steering linkage in this car is exposed, and don't let the brain or wires get close to it.