I would suggest reevaluating the pump. Fuel pumps are made to keep good pressure with a relatively low flow rate. Even with just a hose on the end, you will find that the flow rate is not that impressive (1 gal/min) and will not dislodge any material or properly agitate the tank. Try filling a milk jug in your sink in one minute and you will find that the flow rate is quite low. By comparison, a garden hose is on the order of 4000gph. You will not see the 15psi as quoted by the manufacturer because you are not providing the necessary resistance. The most powerful pump that I know of that is made to be an inline fuel pump is a 260gph FASS which still won't agitate things all that well.
And of course, if you go up in pump size, that means the filters need to be increased in size and flow rate or put in parallel. Make sure that any connections that you make will flow well because any restrictions will make a huge difference in the flow rate.