There appears to be some 'confusion' regarding hands free kayak pumps.
Unfotunately all kayak designers, manufacturers and distributors may not sympathesize with your needs.
They have enough to worry about with the costs and bums required to fill the seats!
Since no two kayakers, kayaks and pumps are the same, there will be a different philosophy and approach to the pump installation. You can find a lot of info in the Pump House/What are the best batteries/etc.
Here is a brief summary of my experience.
1. DIRECTLY MOUNTING THE FOOT PUMP ONTO THE FRONT BULKHEAD.
This is a good option since it not only increases the forward storage of the kayak, but, more importantly it decreases the floodable volume of the cockpit (less water to pump out!)
That being said, there are some problems associated with it.
a) The seat must be easily field adjustable to compensate for different paddling conditions and types of footware.
b) The bulkhead must be heavily reinforced, thus increasing the weight.
c) The bulkhead must be positioned for your individual leg length.
d) The resale price of your kayak is compromised because of the above.
e) Removing the pump for maintenance is difficult.
2. MOUNTING THE PUMP ON AN ADJUSTABLE BRACKET
This could be the next best option.
a)The bracket is mounted independent of the bulkhead and the foot peg position and is easily adjustable.
b)The installation requires only one (outlet) hole to be drilled with no need for additional tools.
c )The pump is easily removable for maintenance or for use in another one of your kayaks.
d) The pump outlet does not allow water to re-enter.
e )The total weight of the pump and its bracket is less than an electric set up (with a 1.2Ah gel battery).
3. INSTALLING AN ELECTRIC BILGE PUMP
You will find a lot of posts on this subject on this forum already.
What I can say in essence is, that they are more convenient to use but less reliable.
The inherent problems associated with air-lock and impeller cavitation remains.
There is simply many more parts and if one fails, the whole set up is down.
For expedition paddling, you should consider the addition of a solar charger.
My background is in electronics, so excuse me if I sound a bit pesimistic in regards to this option.
However, on the positive side, the average electric pump empties the cockpit faster than anything else.
Whatever method you choose, you are on the right track.
We should all be encouraged to use hands free operated pumps.
Safety is paramount. Don't compromise. Equip your sea kayak with a hands free pump.
Use the best components and materials for the job, as drilling even a single hole in a kayak is irreversible.
Play safe, get fit and enjoy it.