Utility trailer rehab-tetanus shot special

I sort of inherited this 4x8 angle iron framed plywood utility trailer. And it is rough. Lights and wiring are cracked and need to be be replaced. Wheels don't match, but at least are both the same 15" diameter. Both tires are cracked and go flat overnight. Plywood  bottom and sides are rotted badly. At least the frame seems to be ok. Some surface rust but nothing a quick wire brush and paint won't fix. 

I need to replace the plywood. Had thought about some other options like composite deck boards or diamond plate, but I really need to do this on the cheap and quickly. I figure the original plywood lasted about 20 years with zero maintenance or care, so I'll just grab a couple sheets of 4x8x 3/4" G1S. Wondering what a good way to finish it would be? Just some good exterior paint and recoat every few years? Bedliner? 

Trailer will be used for trips to the dump and compost heap. Will be stored outdoors and will remain unloved.  Any suggestions welcome.

Cheers,

BJ

Agree that diamond plate is over budget.   I got one sheet free from a buddy (yeah, not counting my labor there...)....the other 1.5 sheets cost a bunch; but they still look good 20 years later (wife is happy).

I'd say go with Advantek or CCA treated plywood and don't look back!

3/4" marine grade ply will last a really long time. Especially if painted. 

My dad's old yard trailer had a steel sheet floor and marine ply side walls. It survived for 30 years of yard use and is now being used be the guy he gave it away to.

Asked a similar question over o Corner Carvers about a decade ago.  I had a 16' flatbed car hauler with  2x6  (2x8?) pine decking. After spending 7-8 years stored outdoors, in MI winters, the constant thaw and refreezeing broke up the structure (fibers?) of the wood. After 10 years, you could step through the deck in places- at 15 years when I redecked, I could pull the wood apart by hand.

The consensus over there was pressure treated 2x6, primed, and bed lined.

Think I'm with birdmayne here- Marine ply primed and painted or bed lined

I have a similar one from Tractor Supply; maybe 20 years old now, stored outside the whole time in FL.  I put 3/4" marine plywood in it originally.  Just changed it out last year and the old sheet was still mostly structural, just very ugly and battered.

Try a water based pentrating stain, rather than paint.  It'll need to be recoated every 5 years, but unlke paint scraping, etc., there is no prep required.  Just reapply another coat or two.  

Jack