a) that profile is usually just noise abatement, if it were obstacle clearance then the THR RED altitude is modified, not the ACCEL alt in my experience. If you are worried about terrain then you can always select speed (it doesn't have the same protections as SRS but by this time you're 2000'+ agl and going up, so not a huge worry). So it's not the end of the world if you pull OP CLB by too early.
b) why not pre-select the cleared FL (in this case FL80) and delay pulling OP CLB until the FMA changes to CLB mode. I know you said you had an alt constraint but there's no reason you can't delay 'pulling the knob' until 3000' - you're not going to bust your level and the FMA change can act as your cue to select OP CLB if you're worried about forgetting.
c) whatever you decide, tell your colleague! It's important they know what you're doing, if you deviate in any way from 'standard' i.e. from what they would expect.