A friend of mine suggested that I use a sheet of 1/2" or 3/4" plywood as a skidplate under my Zuki?? I've had enough plywood boats that they take a real beating on rocks without breaking easily.. has anyone ever heard of doing this?? I can see the validity of it, as laminated plywood is strong enough to bounce off rocks, and would be cheap & easy to swap out when damaged enough..

BUT unless treated it would hold moisture and dampness up to the bottom of the chassis.. My zuki was undercoated by a previous owner, so I dont have any chassis cancer now anyways..

I do not see 3/4" plywood as being light, and I doubt that 1/2" plywood will hold up on rocks with 3,000 lbs on it. 
The front skid pan must have been an option as I have crossed paths with several of them.   Do it right the first time so it doesn't fail on a trip, when you need it the most.
I built my first skid pan out of some SS plate I had on hand.  It was too light and would bend when turtleing over rocks, but it did provide protection. http://www.zukiworld.com/forum/build-diaries-how-to-diy/tracker-full-length-skid-pan/
I have since built a heavier version two piece that has held up much better.  (Perhaps I should go back and update it.)  But this was to show how easy it is to create one.

Calmini has skid plates at $150 for front and $109 center, and $75 for TC.
This is what I have been running for years now.

a $150 skid plate in the USA, is going to cost $500 or more in Canada.. everything here is a hell of a lot more expensive than in the USA..

I wont be doing a lot of rock crawling in my zuki, but I dont need a blown oil pan in the bush either. My rig is going to be setup to get me n my pop out near creeks n rivers so we can collect material to bring home to our Sluice.. We're not allowed to sluice on rivers & creeks here in BC, without a lot of a government BS.

a $150 skid plate in the USA, is going to cost $500 or more in Canada.. everything here is a hell of a lot more expensive than in the USA..

I wont be doing a lot of rock crawling in my zuki, but I dont need a blown oil pan in the bush either. My rig is going to be setup to get me n my pop out near creeks n rivers so we can collect material to bring home to our Sluice.. We're not allowed to sluice on rivers & creeks here in BC, without a lot of a government BS.

I have seen where you Vancouver Island guys wheel.  It seems that what is not rock is trees growing through the cracks in rocks, or logs.  (I am not disparaging Vancouver Island, just that there is some pretty heaving wheeling going on up there.) 
The skid pan in the photo was bent using the bucket of my tractor, and the wings were welded on.  My point being that a good skid pan can be made or purchased for less than $150.  A sheet of 3/4" plywood is fairly expensive down here.  A family member works in a metal fab shop, so I don't know what the cost of actually having  one bent would be, so I listed manufactured prices.  My tracker was built to be able to go to the end of the road and be able to turn around and drive back out, and I have found out that the ends of roads in some places are harder to get to the end of than those in Washington.