I must agree there is danger in sanding too much. It is possible, in theory, to sand through the top layer of veneer.
On the other hand, I have sanded units which I've built out of birch ply from HD and a specialty shop. The latter was Woodworld in Plano or Richardson, Texas, BTW. Good stuff there.
I would not hesitate to use a sanding block with very fine paper. I've never sanded through the top veneer. On the other hand, the paper backed veneers are paper thin veneer and I did ruin one of those because of a bump in the glue underneath. UGGG.
Also, power sanders can be a real danger and so you have to exercise caution with those.
One thing that can go wrong with hand sanding is that at the edges of the piece there is a decrease in the contact area, and increase in pressure, and that is where you can run into problems. A sanding block prevents that. You have to keep light, even pressure and take care not to bend it over the edges.
Many store bought blocks and home made ones use 1/4 sheet of paper. That gives you a block about 3 inches by 4 inches. Not bad. However, a better approach is to set up a block to take 1/2 sheet. This means you have more area. You are sanding with a longer block. Therefore there is less danger of bending it over the edge if you keep, say 75% of the long block on the surface during the strokes..
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This sanding (with very fine) is important because it will remove any residue of the stripping process. The residue will cause the paper to clog at first; assuming it is present. When the surface is clean you will get clean sanding dust. Do buy a pack of very fine and change it out when and if it clogs. Sandpaper is actually the cheapest part of the project. .
My comments about water borne finishes were based on the assumption you want something with no stain and as light as possible. People here have used stains which get closer to walnut or mahogany. Never quite the same but closer. HD has Minwax families including sanding sealers, pre-stain sealers, stains, and varnish. I like the wipe-on varnish. That is different than water based.
Patience is everything. As I always point out, you have to practice on some scrap pieces first. Again, the bottom hatch is a possible training ground if you have nothing else. I got very good results on projects doing one hour every night for a week. You can't do that in seven hours in one day.
Gil