Gluten free loaf ala Bananas and Lemon

After scouring the net for gluten free, soy free, dairy free I found this recipe. It reads as a loaf, I turned it into a cake and it was well received. It also does not look anything like the photo on the link page. I could have sworn this was the one with the almond flour, but I made so many, they all kind of got jumble din my brain. So no, this on eis no tan almond flour cake! Recipe as listed:

Gluten free banana lemon loaf

1 cup rice flour
1 cup buckwheat flour (I usually just use 2 cups rice flour)
3 tsp baking powder
1/2 tsp salt
1 cup plus 2 tbsp margarine or butter
1 1/4 cups sugar
23 oz bananas (I use 3 average sized ones)
4 large eggs
4 tbsp icing sugar (I just use regular sugar)
1 tbsp lemon juice

Preheat oven to 350F

Sift flours with baking powder and salt.

Beat the butter, sugar and bananas together until smooth and then briefly stir in the eggs.
Stir this into the flour mixture until blended.
Pour into a large loaf pan and bake for about 1 - 1 1/4 hours or until a skewer comes out clean and the cake is just firm.

Cool for 10 minutes and then mix the sugar with the lemon juice and drizzle over the top. (I like it lemony so I use more lemon juice)

Changes I made: I used brown rice flour. I used Spectrum Shortening instead of butter or margarine. And I only used 3 bananas. Measuring out 23 ounces of bananas made the cake very gooey and next time I will use fewer. I did use the buckwheat flour. The rice flour is just too grainy for me to use on its own.

Update: Um, I forgot to mention that the margarine is not allowed in the wedding cake. I used spectrum shortening in place of the shortening, but I reduced it to 3/4 cups and added a bit of canola oil mixed with a couple tablespoons of lemon oil.