Re: slightly soft floor remedies
When you start talking about the sole being "soft" there are no "quick and easy" fixes. Rot is best thought of as cancer. Sure, you can choose not to treat cancer, but that never ends well, nor will the rot in the sole of your boat. And if you're not 100% sure, it's always worse than you hope it is. While it may be quite a bit of work, it's not rocket science and anyone with a small amount of do-ability can tackle and complete the repair.
The boat has stringers that you really need to inspect by drilling samples. If the "sawdust" that comes out of those test holes is anything outside of bone dry, then the stringers have got to be replaced as well. You in the structural integrity part of the boat and there have been plenty boats sink because of ignored rot.
Putting a layer of good wood down over a layer of bad wood is absolutely a waste of time and money. It's no different than choosing to wear a ball cap over the skin cancer the doctor found on your head. Sure, the person looking at you may only see the cap, however, the problem is still there, but now a little harder to get at.