Lacomus, it is timely that you mention the ?'Diamond' problem, as I for some reason missed your two top of the page posts. First let me say that I did not actually try my solution, it was just mathematically possible to ?'cut the corner' to reach the centre.
I feel sure your solution would also work, and there may well be other solutions. You mention the weight of wood, but what if they were cheep ?'scaffold planks'? They would come in at 25/30 lbs. Marine ply, perhaps a ultra light composite material? What if the lake was only 1inch deep, you could lay the planks down on the surface and walk across, before the acid got to work.
My point is, you have to work with what you think you have. Very few answers are set in stone and cannot be improved. It is good to have you on this site and I enjoy your way of thinking.

I would never have come up with the correct answer to Frank's question. In fact, I am still trying to understand the logic, but it was good.
The young girl question.
Answer: She reasoned that if the guy appeared at her mother's funeral, then he might appear another family funeral.
If you answered this correctly, you think like a psychopath. This was a test by a famous American psychologist used to test if one has the same mentality as a killer. Many arrested serial killers took part in this test and answered correctly.
We live not on land, or sea.
We have two eyes, but cannot see.
The closer you are, the more you can reflect,
on whether, your answer can be correct.
But, in the end only lies.
We are
Additional line.
We close at night, and open at dawn.
You are a pyramid construction manager in ancient Egypt. One of your chores is to move great stone blocks from quarries to the pyramids, hundreds of miles away. Unfortunately, due to a flying saucer union strike, the blocks cannot be levitated as usual.
You hit upon the bright idea of rolling the blocks on large wooden rollers. Each of your rollers has a circumference of two cubits. For abstract booking purposes, we will not go into here; you need to solve this simple problem:
For each complete revolution of a roller, how far will the block move

Assume there is no incidental sliding motion.
Take two ordinary U.S. quarters and touch them together. Tough, huh?
For those of you outside the U.S., or in extreme poverty, a quarter is a circular coin about 2.4 cm in diameter, and a thickness of about .15 cm.
Now take a third quarter and position it in a fashion so that it touches the other two. How many quarters can you add so that each quarter touches every other quarter
How quickly can you find out what is unusual about this paragraph? It looks so ordinary that you would think that nothing was wrong with it at all and, in fact, nothing is. But it is unusual. Why? If you study it and think about it you may find out, but I am not going to assist you in any way. You must do it without coaching. No doubt, if you work at it for long, it will dawn on you. Who knows? Go to work and try your skill.
One for the Math's guys.
An eccentric individual makes it is life's work to tie a rope around the earth's equator. He buys a lot of rope and makes the attempt. A rival of his, not to be outdone, decides he wants to tie a rope around the earth's equator that is elevated from the ground by one yard at all points along the rope.
How much more rope does he need
Assume the earth is perfectly spherical. Note. It is NOT the total length, only the EXTRA length.