Flour for Crackers?

I was wondering if anyone has used a low protein flour for crackers, like pastry or cake flour. I have found that when making baking soda crackers, they are very dense when I use all purpose. I'm trying to get them light and airy like saltines or even Goldfish texture. I have some cake flour and Graham flour (whole wheat pastry flour) that have about 9% protein. Would using that make the cracker "lighter"? These are for my kids and they like it when I add rye and whole wheat, but not the toughness that comes with it. I promised to make heart shaped crackers for my kids today since I didn't have time to make them over the weekend (one of my kids was sick).

Cracker Recipe:

96g whole wheat pastry flour (9% protein)

60g rye flour

60g all purpose flour

1tsp baking powder

1/4tsp baking soda

1/4tsp salt

1/4 cup cold butter

180g water, added a little at a time (I use apple cider sometimes)

Roll out dough to 1/8" or less. Bake at 375F for 20-30 minutes. For 1/4" thick crackers bake at 350F for about 25 minutes.

Edit: I went ahead and baked it with the cake flour. The crunchiness was what I was looking for.

My changes: I did not, however add butter and instead just added a tablespoon of olive oil. I used Lactose-free whole milk milk in place of the water. It needs more milk as the dough and crackers were quite dry without it. I did not use butter because my youngest has to be dairy free right now. He had a stomach bug over the weekend and his tummy isn't ready for regular milk yet. I also did 1/2 tsp of baking powder and 1/2tsp of baking soda because that's what I usually do when I use apple cider, but I forgot and used milk instead, oops. I'll post a picture later. The hearts came out very cute and held their shape just fine. Now to rouse him up from his nap to go pick up his brother!

Flavor: it was just mediocre. I think possibly more rye, less wheat next time, maybe use an egg yolk or two in place of the butter, and a bit of honey would help. Oh, and start the baking timer at 8-10 minutes. Any more than that and it's going into burn territory for shapes that are only about an 1" big.