I'm not saying this is the right way to solve your issue, just how I did it with the same boat.
I had a similar concern re strength while considering a bilge pump on a SR4, (I had a 60hp Merc). The set up I finally settled on was:
1) Blank of the flooding hull with a removable (screwed rod and internal bar) stainless steel disk. Rubber grommets cut to size for the two at the front of the hull.
2) Remove the internal sump plug.
3) Fit a bilge in the flooding section and run the hose through the sump plug hole into the boat and out over the transom.
Take the power cable through the same hole, run to the dash and switch it.
I used a whale in line pump for a water supply for a caravan fresh water supply. I found it emptied the flooding hull quickly enough> I kept waiting for it to fail after using it in the sea but it was still going strong after 8 years (as the boat got nicked it might still be working for all I know).
The benefits I found were no additional holes, no water sloshing around in the boat (wet skiers etc) as it ran into the flooding section via the sump hole.
As for space I also had a hummingbird depth sounder fitted in through the big hole, along with the pump, it was a little sore on the fingers, but it can be done.
The only concerns I would have if doing this again would be, if you don't make sure the flooding blank is water tight, over night the water will fill the flooding section come up through the internal sump plug and fill the boat, no real problem as the bilge clears it. Make sure your battery terminals are above the filled boat water line, if they get submerged they turn the inside of the boat into a battery..
any metal in it will dissolve over night, just another little experience..
I left the hose and power line free in the internal sump hole, if I were doing it again, I’d silicone them in place to seperate the flooding hull and the inside of the boat.
Only a suggestion, but it worked well for me for a number of years..