such as your Penguin would require a hatch to be cut in, which would then need to be well sealed or you have created a leak into your lower hull. Not commonly done on the the small boats, IMO. You will have a lower area at the rear under the well where your deck  drain is--this is where most people fit an electric pump. This is done because with this configuration of boat, it is the only way you can get water off the deck as the bung which drains the deck area will be well-nigh impossible to get at when the boat is in the water, and especially in an emergency situation such as taking water over the side/transom. In regular use you will find it very useful for getting rid of deck wash-down water, can't really see how anyone could live without one. Get a good brand 2000gph (or larger) which will need a 1" hose and skin fitting. Put the skin fitting up as high as you can get it in the side of the hull.  Even this will struggle to clear a deck of a lot of water quickly. Pumps fitted in this manner are normally switched manually, auto switching of above deck pumps is really unnecessary.

Essentially, with smaller glass boats, you are relying on the trapped air under the deck , or any flotation foam fitted, to keep you afloat. If you develop a crack in the lower hull, or a badly installed skin fitting leaks, you are filling up the lower hull. Which will probably not be immediately obvious. You won't necessarily immediately sink, but it will get very heavy in the water and unstable. Having a bilge pump with a float switch, working on auto, can certainly help, as you will also be aware that the auto pump keeps coming on, which indicates a problem. The fitting of a pump will require you to identify an area, low in the hull where you can fit it, then the cutting of a hatch, and also a method of cable entry, both of which can actually cause water toenter the lower huil from above. All of this costs money if you don't have the ability to do it well yourself, probably more money than you would want to spend on your boat. I would suggest that a better approach would be to drain the lower hull through the bung ( you will have two bungs, one for above deck, one for below) after every use. Little or no water should come out of this one after a day in the water, a small amount will commonly leak in from around the bung itself. This sort of hull rarely suffers catastrophic failure, there will be a trend, and you can spot it easily by draining every time you use it. And leave the bung out, to keep that under floor area aired out. I've seen people who would refuse to do that " because they are afraid they won't remember to put it back in" Doh. I'd suggest they should take up lawn bowls instead.

All of this pertains to smaller glass boats, used off a trailer. Boats left moored, and larger ali boats with sealed decks, are another subject entirely.

  I have the same issue on a 5.2 Nautiglass hull - sealed deck - no bilge pump in the bilge ...set up exactly as ranmar850 describes- 2 deck level bungs for washdown purposes - and a small bung below waterline level which collects a little water if I have been out all day - I have a high capacity pump set up under the transom well at deck level  for just that scenario- a wave breaking over the stern or something along those lines and having to remove a lot of water quickly.. have not yet had to use it - nice to know its there ....

 I have a Penguin Huntress, also with a sealed deck and 4 bungs.  My bilge pump is located in the cavity under the motor well near the in-floor fuel tank.  Didn't have to use it much but good to know it's there.  It's one of the first things I test before I go boating. 

Agree with the above and that an auto is not crucial on the deck/floor however if you do fit an auto pump (above or below) place the float switch at the rear - even water surge or other objects may/can break the float switch otherwise rendering it useless. also need to make sure there is nothing including wiring or flotsam or other lose objects that can move and jam/stop the switch from operating.

Bigger the better but keeping battery capacity in mind.