It may be that a third year of decent assessments is the trick...Just because there is a shortage of on-camp mil orientated secondary duties does not mean there aren't any secondary duties...Think of Round Table/SSAFA/TRBL/Cubs/Scouts/Cadets/PTA etc.
Try to do something that cant be seen as self-serving e.g. Say if you had a kid who played football for the local team and you helped to coach them that can be construed as being self-serving and therefore not a good 2nd'ary duty...Apply that rationale to your situation and choose wisely and quickly...Something involving the handling of money is the best...
You may and probably are the greatest one of whatever you are and do but there will be another 8 dozen just as great as you...As much as it pains me to say this it's what you do extra that will make you stand out...
As for the PVR'ing then taking promotion thing...Nobody ever said that life in the mob was going to be fair or even make sense!
Good luck...
In my view, picking the right secondary duties is more important now than with the F6000. The duty must compliment what the subject is good at, or show-off something that the primary duty does not. Like Mickwreay said, be good at the job and shine. In practice the 1st RO should really have to lever-in the secondary duty into the main narrative/potential if you give him enough to write about. For a really good candidate, 1850 characters isn't a lot of room.
I'm a firm believer in having the brass-neck to tell your 1st RO what you expect in your appraisal during your mid-term interview. "I'm really keen to get promoted, I think I am ready, this is what I am doing about it" - keeping to the fore what you are doing and making your 1st RO focus on whether or not you are on-track to achieve what you want. Its not a case of "look at me look at me", its quietly getting on with your job and role within the team whilst making sure its noticed. If your achievement is shared - make sure the others get the credit that is due.
Keep a 'boast-sheet' throughout the year (I keep mine as a note in outlook) as and when you do things that are worthy of note. Careful here, since 1st RO needs to be in tune with what you are trying to do in presenting a long list of stuff that he may not deem worthy of inclusion...that's fine because he can ignore what he doesn't use.
Lots of small things can demonstrate a larger point. By doing this throughout the year, you'll have it all to hand and impress your 1st RO when you hand him a piece of paper with your achievements on 10 mins after he asked. Present it in DW format like a LM, even if you don't normally use DW. It may not get into your assessments, but it will be another thing that Renton can do, and will add polish. I was amazed how many folk on JMLC couldn't write a loose minute or a memo....and IMLC if I am honest. Your 1st RO (should!) be grateful if you give him some good material to get the juices flowing.
You are being promoted against your peers in the whole of the RAF not just your section - but for a 1st/2nd RO to say "Out of 10 SACs Renton is the most
effective by far....blah..blah" is a powerful statement that jumps out of the page, and one to aim for...whilst still keeping friends!
Be a positive and cooperative within the team and seek improvement. As an SAC you can do an OJT course. Once thats complete, you can try and eek out a role for yourself - perhaps helping with OJT with junior members of the section. Think, next rank and try to be a Cpl in everything but the rank you wear, have the attitude of a good JNCO.
Dont get involved in nastiness and back-stabbing, it gets noticed. Being positive when things are sh!t is an important one and will get you noticed, do it with conviction though and not just when you are being watched. What your peers think of you is a big factor and if they see that it wont go down well.
Avoid "other shiftisms" and generally give folk the benefit of the doubt if you can eg. when you arrive and the place is in a tip or there is loads of work on - it may be that they;ve had a crap shift where nothings gone right, we've all had them. Yes they may have left a load of work, but that is what you are paid to do and while everyone else is bellyaching, just get on with it.
Leave all your whinging for the 'goat!
There are others on this board better qualified and more experienced than myself and this is only how I see things. Best of luck.