Need advice with my large print. I have a plan, need opinions.

I am no expert by any means, but  I have a couple ideas you could try though.  You could try less infill.  But my first attempt would be to split it and print two (or more) smaller pieces and use abs glue to put them together.

If your brim is running off of the bed, maybe make the brim less?  You can change the settings.

What is your bed temp set to?  I had to crank mine pretty much as high as it can go, because I use a floor tile as my bed, so even with it set to 110c, the tile only goes to 55c.

Since you too are clamping something, I say that you should probably crank the bed up as high as you can go safely, within the limits of the machine.

I know someone else on the forum recommended this.  Print a bit, like two layers or three layers, and then pause the print, and then take acetone and a q-tip and then dab the acetone with the q-tip to various parts of the brim to fuse it to the bed. then resume print.  I haven't tried that personally but it sounds like it would help with this massive print, since you're essentially spot-welding it to the bed.

The "wavy" part is caused by extruder pulsations.  The extruder does not move smoothly (since it moves so slowly, and is not highly microstepped).  You can feel it if you grab the filament near the extruder while it is running.  The abrupt movements cause pulsed changes in the rate of plastic flow.  When the plastic is smashed so thin, this manifests as "waves."  This same pulsed behavior will cause patterns in regular surfaces of your parts (moire patterns).

Some wise boarders here suggested adjusting the stepper driver to smooth out the stepper motion hence reducing the amplitude of the pressure pulses.  Also suggested was the ultimate fix: replace the driver board with the DRV8825 unit that allows 1/32 microstepping.  It is pretty cheap.

I have adjusted the stock driver with good results (turning a really tiny pot on the board for a good balance of smoothness and torque) and no ill effects.

Assuming you do not want to redesign the part:
1. Glue it down.  I am quite convinced of this.
2. Reduce the temperature delta in the part while building it by:
-         a: Turning off fans intended to cool the filament.  Keep the building part as warm as possible.
-         b: Putting an enclosure around the Doodle  (cardboard works as experiment).
-         c: Use a fairly hot bed.  With the enclosure, this helps keep the entire environment warmer and -             closer to the extruder temp.

Redesigning the part:
The walls are the culprit.  Using a lower density interior won't help much since there is already enough void inside to manage stress that is trying to pull up the corners.  If you printed the part with only exterior walls you would still be having the same issues, as witnessed by all of the examples of warped project boxes.  Conversely, if you printed a similar brick entirely at 50% infill (no perimeters) it would not warp.

You need walls on your part.  Anything you could do to make them thinner, either entirely or in strategic places, would help.

Hope this helps
(Glue it down.  Call me a dufus publicly if it does not work.)

Have you also set up the driver to microstep?

You want the SOLVENT for the adhesive not the adhesive.  It is on the same shelf at the big box store (Oatey #30795, yellow can).  If you can find some MEK, just mix it 50-50 with acetone and you will have the same stuff.

Sauce:  Dissolve ABS in the solvent to about the thickness skim milk, maybe even a bit thinner.

Use BOTH the hairspray, AND the sauce.  Hairspray 1st.