Okay, in the first place, say Wyatt did find the remains of two people who were what we might call giants. How would he be able to tell one way or the other if they were Noah and his wife or not? Unless there was a grave marker with their names on them (and we don't even know the name of Noah's wife), they could be anybody.
Second, Moses just recorded what God told Noah. God gave the measurements to Noah in cubits, but we don't know how long a 'cubit' was considered to be before the Flood. Noah could very well have used his own cubit; again, there's no way to tell and it doesn't really matter. I think what's important is the proportions of length to width to height, not the exact measurements of each. These proportions have since been proven to be the most stable design for a ship so that it is unlikely to capsize.
And just for the record, I highly doubt the decking would have been four feet thick. There isn't even that much space between floors of modern skyscrapers, so why would they need it to be that thick on a ship? I'd say maybe one foot, max, and probably not even that much.