For programmatic ads you should be happy to earn $6 eCPM with 6+ ads on the page, so about $3180/mo. With that you would want to be prepared for seasonal changes, like great earnings in the 4th quarter, then rates falling in half in January.
I admire your effort to avoid tracking. Most traditional sources of ad spend are somewhat incompatible with that model, so I wouldn't waste time worrying about ad networks and agencies. Try to discover the organizations that would gain the most value from exposure on your site, then sell them fixed placements with annual contracts. You can also sell bundles of impressions, but honestly its not likely that you could do so with much scale based on self-reported impressions. That is to say, advertisers have no reason to trust publisher metrics; they only trust trackers they can control or audit. Bot traffic, from 3rd parties to your own testing/RUM tools, make impression counts almost irrelevant, even if you are acting 100% in good faith.
Ideally, with fixed fee ad contracts you'll have advertisers you and your audience generally likes, and those advertisers have some motivation to support your community and showcase their sponsorship of it, since more traffic for you means more value for them.
Your advertising page would do well to contain a web form, and not put all of the terms up front. You can be very candid with your potential ad customers, but there is no reason to scare them off on your landing page. Maybe a separate URL for the ad terms?
In this context, I think referring to the program as a sponsorship vs advertising makes sense. Ad buyers have not been keen on doing individual site ad deals since the early 2000's, but there is always money for sponsorships- with less expectations of metrics and more warm and fuzzy feelings.
I wouldn't expect you'd receive a lot of traffic from inbound traffic. Your users would make for a good source of insight about who might make a good sponsor, and may become a sponsor themselves.
If you depend on ad revenue, you're either in the business of programmatic ads, or your in the relationship business. If that don't come naturally to you, find somebody with existing relationships with check-writers and pay them something like 25% of sales.
I like your site. I would suggest looking into your analytics for ideas about potential sponsorship partners- at first blush (thanks you your awesome public analytics) it looks like productivity, development, and music are decently popular categories. Based on that Todoist, Zapier, & Spotify could be good sponsors, or maybe startups in those categories that align with your values.
Best of luck!