Could I make a suggestion here. I plan to use Exped flat valves on my two boats, partly because we have Exped sleeping mats now and it makes sense to use the same schnozzle pump for both. These are excellent little valves anyway, quite unobtrusive and well proven to be reliable. The only negative is the cost – you have to cannibalise an Exped item to get them. If you want a deflation valve as well as the inflation then an air pillow is cheapest, or if you want just the inflation valve (which can also deflate) then a replacement tube for their TT mats is cheapest (at least in the UK). Once cut out, the valve will have a large circle of TPU fabric making it easy to glue onto something.
On the boats I will use one inflation valve near the stern, and use that to release the peak air pressure and the zip to release the air volume. The inflatable floor will have another, probably also near the stern so as not to be blocked when the boat is rolled up.