Claude,
Nice job. In my case, after the bottom removal, I went to work blasting away with a hose nozzle and eventually my high pressure washer through every opening I could find in the liner. That included starting back at the cutout for the strut bolts, the shaft log, front of the engine pan, etc. I sprayed to catch the underside of the sole and through all the holes where the waterlines went through various spots. Don't forget to pull the table post receiver as well. There was a lot of accumulated stuff in there that made its way to the very bottom. Find a spot to stick a shop vac hose on blow to aid in drying. After a couple of days the difference is noticeable.
Chad,
I only cut away enough so that the largest bilge pump I could buy would just fit down there. I have a West Marine 2000 GPH with integrated float switch. Its an elongated shape so it fits nicely. I see no need to cut up any higher except for pump clearance. It will save you from rough cut edges grabbing you when mopping up periodically with a sponge. Once the water turns that last corner its going to fall in the bottom and the pump will suck it out. It doesn't matter if it's exposed on the way down. And like Claude says, there is some bonding to the hull up there which will make the removal more labor intensive. Later when I got a multitool I did cut the points off the opening and it was hard on those cutters. I used the half circle flush cutting ones because you can rotate them to fresh teeth and maximize use of them.
The other big deal for me was to go to the dripless shaft seal. This last haul out when I put a service kit on that seal was it for me fighting another press on coupling. That's been swapped out for a split coupling so even that job should it be required is going to be a lot easier.
Allan