How and if to advise editor about suitable referees for my paper

This certainly sounds like it could be communicated through a cover letter. This does not guarantee that your comments are actually being read by the associate editor, though - at least in my field, cover letters are uncommon enough for journal papers that I typically don't even check if there is one if I get a paper to handle. However, it is unclear to me what practical other ways you have to communicate with a handling editor where you don't know yet who it will be.

That said, you never have a guarantee that the editor will take your input on reviewers into account. Personally, I tend to be fairly sceptical about "suggested reviewers" or anything that approaches this - maybe I am too suspicious, but whenever authors suggest a reviewer, especially when not explicitly asked to do so, I immediately assume that this reviewer will be in some way positively biased, even if no conflict is obvious from the outside.

So my summary is - sure, (briefly) explain your reasoning in the cover letter, but don't get your hopes up too much that this will change substantially how your manuscript will be handled.

In biophysics, many journals actually ask authors to provide suggestions for reviewers. If you have not done so already, have a look at the submission system and the author guidelines to see if this is the case for your journal.

Otherwise you may be able to choose the editor, so choose the one that you think understands your paper and has the right reviewer network to choose from.

In any case: make it clear in the key words and abstract of your paper what it is about. The editor will use these to choose the reviewers.