Building a 5x9 on a 4x8 frame

Any tips or pictures of people who built a 5x9 tear drop on a 4x8 trailer?
I have a boat trailer that has a very long tongue so was thinking about creeping ont he tongue a bit to make it more roomy. Also the 4x8 is inside wheel so was thinking of framing it to the outside of the wheels, adding some storage underneath and making the inside big enough for a queen bed since it would be for me, my husband and our lab. Haven't found many pictures or info on people doing that.
Any info would be much appreciated!
Thanks
I have a boat trailer that has a very long tongue so was thinking about creeping ont he tongue a bit to make it more roomy. Also the 4x8 is inside wheel so was thinking of framing it to the outside of the wheels, adding some storage underneath and making the inside big enough for a queen bed since it would be for me, my husband and our lab. Haven't found many pictures or info on people doing that.
Any info would be much appreciated!
Thanks