I have been a physics technician at an academy 11-18 for 6 years. I am a member of the ASE but I read the RSCiTech forms and it did not seem to apply to me. Seemed more suited to somebody working in research. I don't think I qualify. I do advise non specialists and helped produce new experiments for use in the new GCSE and GCE A levels but that doesn't sound like it fits the bill when you read the application.
Yes, unfortunately a lot of the language used when the competencies were set out by the science council is better suited to research or work in industry (this is after all where the largest proportion of the members of these professional bodies are working. I've just taken a look at the forms and guidance documents used by the ASE and they perhaps have not made it as clear as possible how it's members might meet these requirements. It should be perfectly possible for a technician such as yourself with several years experience to qualify for RSciTech. For example advising non-specialists about an experiment as you mentioned above could be used as evidence towards your interpersonal skills requirements. Developing new experiments for GCSE and A levels could be evidence towards application of knowledge (A1 or A2).
I only have A levels, and no evidence of them as I took them nearly 45 years ago, QCF5 is a degree. I ran an engineering company for 21 years and have not had to produce a certificate for my education since I was in my teens.
In fact the only qualifications I have certificates in anything is as an able seaman, which isn't a lot of help!
The educational requirements shown are often exemplifying and there is some scope to take into work experience as well. However for RSciTech this requirement is QCF3 and your A levels would meet this requirement on their own..