DWest I thought that sounded about right. less is more and many are already making mid-level surface area reefs which still carry quite a fish load if desired (bare bottom, rocks are the main filter like u said, not much extra surface area stacked in a sump as its kept open-space for detritus access/removal).
most reefing is so far beyond overdone in active surface area (rocks, sand, plus things in sump for surface area, and in many cases filters hang on too) that over just a year or two the compounding really costs lots of stress and invasion tradeoffs. open-access for detritus removal, during expected water changes a couple times a month will indeed produce a running reef and you can keep corals too, attached to the rock surfaces. they don't require fancy gear, I have friends that keep corals in fishbowls. a 60 is a really great start for allowing fish too.
If you own a reef DMat that is 60 or so gallons, a low fish bioload (pick your lowest number favorites) and mainly live rock as the surface...the rest is either glass surface or plastic acrylic if the sump is such...you'll be able to see the compounding waste vs sink it into a sandbed for pricing later in 2023
that's the lowest maintenance there is, a low surface area, low catchpoint high throughput reef. the water can just mix between upper tank and sump and rocks and it'll all work fine. no extra gizmos attached. a nice skimmer cleaned regularly will help tremendously too in your algae work and design.
*most people want a sandbed for the looks, I have one but its kept clean. its also ok to experiment with add sand/don't mess with it (probably 80% of current reefs are like this) but we're seeing in the invasion work threads there's quite a price to storing up waste, should some unlucky hitchhiker find a way in.
this is handy pre planning for sure, to consider. you could even run the 60 without a sump as an old-school all in tank setup, with a hang on back skimmer. that means no plumbing required, might be a nice option. by keeping the fish loading low, as in maybe 2 super nice clownfish and a goby, you offset all the major storage removal work/machinery a typical dense reef requires. and corals can be glued to rocks easily with superglue gel, and they'll grow if the lighting is right.
