I dug around some more; somehow the root part of SRK is screwed with my phone. I won't let me run ADB sideload and the error I mentioned earlier is due to the fact that the TWRP supplied with SRK cannot mount the /data partition, and this is needed for the custom recovery install.
Paulobrien's TWRP version will allow sideload though, and going with his version got me as far as being able to start the ADB sideload option (in TWRP), without getting any errors. SRK then gives me "error: device not found", and digging some more turns out that my phone is most likely unauthorized, even though I made 100% sure that the key was accepted in dev options, revoked, and authorized again to be sure. Still no go.
tl;dr SRK is probably a nice tool for the people it'll work for - I had to manually install TWRP and root. Dev, please take notice cheers.
Paulobrien's TWRP version will allow sideload though, and going with his version got me as far as being able to start the ADB sideload option (in TWRP), without getting any errors. SRK then gives me "error: device not found", and digging some more turns out that my phone is most likely unauthorized, even though I made 100% sure that the key was accepted in dev options, revoked, and authorized again to be sure. Still no go.
tl;dr SRK is probably a nice tool for the people it'll work for - I had to manually install TWRP and root. Dev, please take notice cheers.