Current Thoughts.

So I am currently undecided about a few things.

Do I keep the gas motor for lift or do I buy a ducted fan?
I will need to buy various things for the gas motor and it would require much more work for mounting. It is also messy as there is no muffler so it just spits unburned fuel and exhaust everywhere.
The ducted fan seems to be in the 20-50$ range for something pretty reasonable. The benefits of having the ducted fan is that I wouldn't require the bonnet. I could just glue the whole top section together and just have it mounted on rods to the lower section as it wouldn't require the ease of access into the air chamber as the gas motor would. Its the lowest and most forward component so that there may be the occasional slight spray hitting it or if it stops on the water it may sink sightly and the that component is destroyed.

How do I go about completing the top of the lower section?
I have a few options here, I'm not sure if its worth using foam as it is only about 5mm high in places and with the expansion It would just have too much excess. Fibreglass, I can fibreglass the whole float, this is messy and time consuming but it would provide a structurally sound piece and would be pretty light. Remote controll plane film,  this is basically just a heat shrinking contact sheet, its light but it wouldn't add a whole lot to the structural integrity.

What does everyone think?

Cheers