AdvancedElements.com

It seems that much time and pressure testing could be saved if one had an equalising set of y-piece tubes which joined all 4 side tubes together.
Then you'd just connect the pump to a single valve and all 4 tubes would automatically be at the same pressure as each other - surely a good thing?
If you're worried about a single chamber's leak emptying all 4, have isolating taps or valves which could be turned after you're happy with the inflation.
4 separate Boston valves for those side tubes seems so clumsy to me.
And so easy to get "ever so slightly wrong".
Unless the top tubes and the bottom tubes should have different pressures to each other - but the manual has no mention of this.
But if that was a need, just join L+R Top and L+R Bottom to have 2 filling points instead of 4.
Given that an accurate pressure gauge doesn't seem to exist in the available pump products, just go by feel and equalise the pressures....

Have you tried this yourself yet.?

No

I did a few years ago make or start to made my own inflatable starting with the bladders.

I say bladders what I should have said was 3 bladders all conected to one pump.

never worked for me .
one bladder always seemed to have more air in it than the others.

I found it was better to inflate each one in turn.

However in the end i never completed the project and moved on to other stuff.

I may once again have another go at it soon who knows.

Makes sense really, the bladder or part of having the least resistance will tend to inflate easier , for example a sharp curve or support point would tend to go underinflated.
The comment about pressure gauge inaccuracy is nothing compared to the
just go by feel approach , certain parts of the kayak , because of the construction just feel beter inflated than others , you can`t get any more innaccurate than that.
There is nothing to stop you checking the gauge simply by inflating something , even just a ball to a certain (AE recommended) pressure and then getting the pressure checked at a more reliable source , afterwards marking your own gauge if need be.
I have found the inline type http://www.advancedelements.com/pumps.html easier to read as they have a built in one way valve,
so not the usual leakage through the pump and having to try to read off
on the upward stroke with the needle moving all over he place.