I think the light is fine, but I disagree with having the cake and eating it too.
Think out side the box here.

The water change idea is good and will work well, I'd just use a solenoid, float switch and refill slowly with a carbon prefilter for chlorine removal. As long as the water change is slow, using say 1/4" lines for filling and 3/8" for the drain the sump should do well and these hard plastic fill/drain lines can be snaked easily into the wall.

As you drain, the refill is right past the sump inflow and goes directly into the return, that way most of the new water is not mixed in the drain.

You can simply run the timer for this do do it right before the lights come in the morning, when you are there.....................and when it is the best time to add CO2(from the tap and dosing) and ferts.

I'd run it for 2 hours or so and you can assume about 60% mix, so if the amount drained is say 200 gallons in 2 hours, about 80 gallons will be "new" water.
This depends on the filter, the flow patterns and the drain fill rates obviously. But you get the idea.

Back to the design:

See #5

ADA Aquatic Plants Layout Contest 2006 Top 10 Winners

Remove the foreground plants, add pure white sand.
Use Crypt Balansae instead of Cyperus in the rear.

This will allow them to play and mess with the sand, but also allow for a nice scape. Mossed rocks make a nice low light solution to the the edges that are darker around the wood to make a nice transition and moss looks good against light sand. These rocks of moss are easy to move and tie etc.

With nice branch wood, eg Manzanita etc, you should be able to make a nice wood lay out and get some Narrow needle leaf java fern, Crypts are easy to find etc.
I'd stick with 2-3 mm light/white sand.

Since you plan on many water changes, I'd suggest not worrying much about the substrate type, you can use the water column just as easily.

You still only need to dose 3x a week.
I'd not automate that personally. Just dose right after the water change.

You feed the fish and adding ferts is no different as far as labor.
Water changes? No way, that's work, so automation or methods to deal with reducing that chore are always wise.

The other things about these plants I've suggested: native to the fishes' habitat/s, easy, low light is fine and they do not need a lot of trimming and maintains the structure of the aquascape. I have 12" plecos in some tanks etc, they knock and few things around, but I do pretty well.

So consider these ideas, you have plenty of light, more than enough for any plant. It's more light than you think........those are PC with nice reflectors, so they are more light having 3w/gal.

I like that someone admits they are lazy, potentially neglectful and then does things to account for their laziness by reducing their work load
Lazy can be smart, which is very admirable versus being hardworking and not too bright. We all have been here at some point, admission of our human failings is part of humility and good for the hobby as well. I think many over look the human element way too much with pets and the acknowledgment is critical to the success of a system/method for long tern care of an aquarium.

We have the ability to set things up to prevent issues and lack of motivation. EI is to get rid of the darn test kits. I do not know anyone that enjoys doing that to date, and I've asked............
Auto water changers, who likes to do those manually or with a bucket? Pythons or a DIY version, solenoids, hard plumbed permanent ball valve fill/drains etc make a lot of sense over the years and life of a tank.

I want my fish to live well, eat well and grow old in these tanks. But I will neglect things at some point unless I do things to make it easy for me to do it and not have to spend so much time to have a nice tank with the fish I also like.

This also makes it easy for you to leave and take vacations etc, which, I do not know about most of you, but I sure like them............

Regards,
Tom Barr