Floor strength

How do, nearly ready to start building my TD, just a few final floor questions.
My trailer bed looks like this (welded it together out of 50x50 3mm i had lying around) Its rougly 8x4

Now if I use 1x2 framing laying 'flat' in the shape of the diagram below, sandwiched between top layer of 1/2ply and lower of 1/4 ply will this be strong enough for 2 people to sleep on?

The central red beam in pic is resting on the metal cross beam of the trailer.
I was gonna use 3 1x6's running lengthways but i thought this would be over kill, factoring in weight etc.
Heres another image to help visualise it. (My rough side template mock up)

My trailer bed looks like this (welded it together out of 50x50 3mm i had lying around) Its rougly 8x4

Now if I use 1x2 framing laying 'flat' in the shape of the diagram below, sandwiched between top layer of 1/2ply and lower of 1/4 ply will this be strong enough for 2 people to sleep on?

The central red beam in pic is resting on the metal cross beam of the trailer.
I was gonna use 3 1x6's running lengthways but i thought this would be over kill, factoring in weight etc.
Heres another image to help visualise it. (My rough side template mock up)
