Frozen bananas

Perhaps a strange query.  In facing the challenge of what to do with over-ripe Bananas, I decided to bake some banana bread --- with a twist.  And here I need some help.

My family likes banana bread but does not hold it as one of their irresistible favourites, so I thought I might boost the appeal by including actual bananas in the loaf (loaves).  So here's what I did:

I carefully sliced a barely ripe banana into two lengthwise, wrapped the halves and froze them.  I made the bread dough and rolled each piece out to a four by 8 inch rectangle about 3/8 to 1/2 inch thick.   I placed a length of frozen banana in the middle of the dough, spread a little brown sugar over the banana, and folded the dough up and over to seal it completely.  I turned the seam side down and placed it on a greased baking sheet for the final rise.

I managed to get the bake times and temperature correct for the bread dough (which did contain mashed over-ripe bananas), but the dough all along the middle center line where the banana/sugar rested remained uncooked and goo-ey.  Now, I cannot increase the cooking time --- the tops of the loaves were well past what I considered to be acceptably brown.  So how do I fix this?

I thought I might roll the dough out thinner --- say to no more than 1/4 inch --- and make up side-supports out of tin-foil to make sure the loaf does not spread too wide.  I also thought that I should forego the initial "spring" baking time and bake the entire works at a much lower temperature --- say around 350 degrees --- to try to keep the top from browning too much.

I am not sure that this can even be done.  I am sure many many other folk have tried something similar to this.  But I do not know what to do.  So I will appreciate all comments of whatever kind (thick-skinned old boy here).