there'll be a good few threads on this, but in summary.
We had a 5.4 with opti 90 on a swing mooring for over 10yrs.
The transom/water line is low and if wind swings the boat stern to waves, they will slosh over.
With no rear well to catch water it makes pumping out hard with a bilge pump. Though it is possible.
If the water comes over it gets exponentially worse until you end up flooded to the tubes, which unless your battery is housed in a console above the waterline, it will short and create a mess, plus cost you the price of a battery and fittings.
We didn't have a well, but did have an auto bilge pump on deck which generally worked. But due to the fact it is often working, if any rubbish/leaves/dirt etc get in and it blocks, or if the float switch sticks, which it will once older or if dirt gets in, then the boat will flood to the waterline. It happened to us, on average once a season from April to October.
Though if you are in an estuary, then without larger waves, the water may not come over so much.
In terms of blocking up the flooding hull, it will give you an inch or so higher waterline, therefore, less likely to flood the boat. We did ours and it did reduce the frequency.
Hope this helps.