Good question Ben, I’m glad to hear that you’re trying to look for ways to publish openly in engineering. (I’m always frustrated that articles by IEEE are paywalled)
Firstly, I’d suggest checking out https://doaj.org/ for open access engineering journals to see if you like any. Bonus, the majority of the DOAJ journals don’t have article processing charges.
Wrt to longevity, there is currently an effort to archive Open Access journals (see here), and I expect this would also get extended to preprint servers if they looked to be in danger. (also, engrXiv is on the OSF Preprints platform, and I assume that COS has some plans for data stewardship, even if individual Preprint servers they host eventually close).
Peer-review is more difficult, you are right in that it is seen as a sign of credibility by both academics and the public. While I agree that traditional peer-review has many flaws, I think the journals that now publish the reviewer report and editorial statements are more useful. If you want to aim for some kind of review (beyond informal commenting), and would suggest looking into these options:
- Pre-print review, see some examples here: Comparing journal-independent review services – ASAPbio
- Post-publication peer-review: F1000 is well known for this, not sure of others (IIRC some ScienceOpen journals do this, or at least allow commenting)
- Try to facilitate commenting by making an entry on PubPeer for your pre-print and putting a link to this at the top of the publication (or some similar strategy).
You might want to check out the Journal of Research Ideas and Outcomes (h/t @antonio.schettino). Not only do they accept a huge range of publication types, but they do also allow post-publication peer review and will optionally arrange a pre-publication review. About I’m considering publishing some items there next year.
With respect to advertising, I think you’ll have to take more responsibility for this if you are primarily pre-printing. One option would just be to mail the pre-print to people from your field who you think will be interested (like the authors of recent works you’ve cited, also current and former colleagues). FWIW I feel that following individual journals is declining, at least in younger academics, so I think this will be less of a problem now than it would have been during the printed journal days.
You might also be interested in this thread, which included a few links about pre-prints in the context of the broader publishing ecosystem.
Also, I can recommend the following book by our late colleague Jon Tennant, it aggregates a collection of his posts on Open Science, many of which discuss options related to pre-printing and open peer-review.