Thank you in advance for your recommendations and advice!

I am currently in the midst of a kitchen remodel using IKEA products. The sink that was recommended to me by IKEA staff, and that I selected is their 2-bowl farmhouse-style, top-mounted DOMSJÖ sink that comes pre-drilled with one hole for a faucet. (http://www.ikea.com/us/en/catalog/products/S59093554)

I live in San Francisco, and like the rest of the state, California plumbing code requires all dishwasher to have air gaps installed (CA Plumbing Code 807.4). We all know that enforcement of this code varies, but I've been told it is required in my area. So my question is how is the best way to go about this? Each time I visit IKEA I've received a different answer and its getting a little frustrating. Here are the various options I explored so far:

1. Drill a hole in the sink and install air gap.

The problem is the DOMSJÖ sink is made out of fireclay. If one is careful, this can be drilled using a ceramic bit. However, the back lip area where this is traditionally installed on this sink is washboard textured which makes installation here problematic at best. I have found one instance online of someone doing this hack, and while functional, the results weren't that attractive because the air gap base doesn't sit flush on the washboard.

2. Simply drill a hole next to the sink through the countertop and install an air gap.

This is how it is typically done when installing an under countertop mounted sink, however this design is top-mounted with a lip over the countertop. I did also however read one person who did, my question however is would this pass inspection because wouldn't there be a risk the water overflow might miss the sink because of the large sink lip between the air gap and sink bowl?

3. Buy a metal IKEA sink, drill a hole in it, and install air gap.

While this would make installation easy, it would not be as attractive and would require a redesign of my current kitchen layout because no other IKEA sinks fit the 36" base cabinets used by DOMSJÖ. I'd also have to upgrade my counter tops from wood butcher block to some other material, because the metal sinks do not mount flush against the back splash and as a result I'll need a single piece counter than is longer than the 8' standard the butcher block comes in.

4. Install a non-IKEA under-counter apron sink.

This would open up area behind the sink for the installation of the facet and air gap in the counter top. However, IKEA base cabinets are not well designed for this and would require quite a bit of customization. Like above, this might also require a different countertop.

5. Install a non-IKEA sink that comes predrilled for a 3-hole faucet and use one hole for air gap.

This has many of the same challenges as number 4.

6. Order a dishwasher that doesn't require an air gap.

Several users in the forums here have reported Miele dishwashers don't require air gaps. Is this true? Before choosing this option how can I be sure my local inspector will approve it?

7. Under mount the DOMSJÖ sink.

This would require minor customization of IKEA's base cabinet and looks doable from online example I've seen. (http://www.cape27blog.com/2012/07/how-to-undermount-ikeas-domsjo-sink/) The air gap could be installed in the counter top next to the sink and water wouldn't be blocked by the sink lip. This make counter top easier to clean up too, but might require different countertop material, if I don't want a seam between pieces. Of all the options, this is the one I'm leaning toward.

Thoughts? Recommendations?