Does my grounding 'plan' seem appropriate?

how about SPD's ( surge protection devices) https://www.solar-electric.com/catalogsearch/result/?q=SPD on AC and DC wiring in multiple locations , as well as connecting the grounding plates together to equalize their potential ?

search for lightning protection here on the forum

The ground wire between the array and house is by code inside the conduit.
That does not bother me for offgrid where it probably will not be inspected.
I would not run any larger than required ground wire into the structure. If your array is #10 wires then that is what I would run into the structure for ground. At the arrary use as big of wire as you can for ground and as Westbrook said bond them and use an SPD.
I like the midnite and delta SPD's and would use one of each.

When you auger the holes (are you anchoring in concrete or ballast racks?)
and put the pipe and rebar in, you can tie it together electrically and make each hole a small UFER ground point,  Spread over 4 holes, you should not get too much current saturation in the soil.  Or do a 6" slab underneath, with rebar between it all, and then it's likely to be an absolutely bomb-proof ufer ground for the array chassis.   Not sure what code wants for your house wire grounding, but UFER was designed for ammo bunkers in the desert
https://en.wikipedia.org/wiki/Ufer_ground
Just don't use a moisture/vapor barrier under the concrete, like my inspector insisted on !

Make sure that your building ground is on the same side of the house as the panels.   If you want more protection, consider a perimeter ground - a loop of bare (no conduit) buried copper around the building.

I faced a very similar situation as you, but I live in central Texas, so our soil type and lightning frequency are probably very different.  Have a look at a thread in which I posed a similar question:  http://forum.solar-electric.com/discussion/22466/solar-array-and-grounding/p1  I did something very similar to what you're planning on doing and so far it has worked well.  I used continuous, bare #6 AWG solid copper wire and put it outside the conduit for the reason you brought up.  I also have two grounding rods out by the two arrays about 125 feet from our house.  In addition to the SPD's (which I've got installed on both AC and DC sides) that have been highly recommended, I also highly recommend you use continuous copper wire.  If you have to terminate the wire and splice it somewhere it can cause problems. 

Hope this helps!  Like others have referred to in this thread...it all depends on what your AHJ allows from a permit standpoint, as well as what soil type you have, the repercussions (i.e. loss of $ or time if struck by lightning) of a nearby strike which will help guide you as to how much to protect your equipment. 

We looked into the UFER ground thing and it just depends on what you're comfortable with.  I had seen some reports that the current actually blew out the concrete near the rebar.  However, keep in mind that a direct strike on almost any system will result in damage...it will always be a risk and there is no 100% truly safe system that is reasonably priced.