I have the kit with the 1.5" SAW's in the rear (since January 2016), still running the stock 265 Nitto's and the rake is definitely there. I have no additional weight in the front or back (i.e. steel bumper, winch etc.).
I was thinking about the same thing (in terms of avoiding the rake). The 1.5" SAW is not as tall perhaps as the 2" Toytec rear springs but the spring rate is different. Something like 12% for the SAW and 10% for the Toytec over the factory rear springs. I believe all T4R models share the same factory rear springs across the 5th Gen line. I still got 2" from the rear and so I think the 2% increase in spring rate over the 2" Toytec AND the lack of added-on weight in the rear still gives 2" on the SAW's for me.
I have tried driving around with sand bags as far back in the trunk as possible while still being able to close the tailgate. Although that resolved the rake look, it drove a bit "floaty" in the front with the tail weight back there. Makes me think a steel, rear bumper would feel the same with the extra weight that far out in back.
So, in answer to your question to avoid rake with the kit I think there are only two ways to go.
1) Consider not getting the rear springs and perhaps work with 1" or 1.5" (if there are such sizes) spacers in the rear on the factory springs? It sounds like you mentioned you would not be hauling much on a regular basis.
2) get larger spacer on the top of the front coil-over and still get the 1.5" rear SAW's. The Toytec kit comes with a 1" lower perch and a 1/2" top spacer. Maybe a 3/4" or 1" (if they exist) top spacer? With this option though you would definitely have to look into an after-market Upper Control Arm.
Toytec might be the better folks to ask, they deal with this stuff every day I am sure. If you do, post up what they say. I would be interested in what you find out as well.