And btw there is nothing actually wrong with 45 minutes for 5(1,2,3) there is no specified rest period in the plan. Short rest periods promote building muscle, long breaks will build your skill, but based on many cycles of learning with this plan (with students and myself) using a bell that is too heavy is miserable and produces inferior results for your much higher effort with a very high risk of injury. What's the rush? Set a very solid foundation with a lighter bell.
How many high quality clean and presses with the 12kg on each side? With a 14kg? Taking 16kg as your 5RM roughly puts your 8RM at 14 kg. For me, that's a lot closer to the sweet spot.
Remember that pull-ups are optional in RoP. If you decide to do them there is specific guidance that allows you to customize to your current level of strength by keeping the same number of ladders as the presses, but to decrease the number of rungs when executing pull-ups. The specific example in the book is if you are doing 5(1,2,3,4) for presses it's ok to do 5(1,2) for the pull-ups.
I completely understand the pull-up elbow issue. I've been there myself. Consider that it may not be the volume of the pull-ups, but rather the way you are executing them that is causing the problem - it was for me. My coach fixed my neck / head position, built up my neck extensor and flexor strength, reinforced my hollow position and got me to focus on pulling more with the pinky-side of my hand and I'm now able to handle much higher volume.
Are you doing the snatches and swings portion of the plan??