We have a 30 year old well that has a reduced flow. Two well contractors have advised installing a 3000 gallon potable water storage tank to assist with water flow when we run the irrigation system. We have plenty of water for day to day household use.

The largest zone on the irrigation system requires 20gpm at 60-65PSI.
Our existing well includes an Aeromotor 1.5HP 20GPM 3 wire pump set at 265 feet. WellXtrol 86 gallon pressure tank and 30-50psi pressure switch are inline with the well pump.

When we start the irrigation system we get about 5 minutes of good flow and pressure before the water starts surging badly. We've been told were out pumping the well.

First and foremost I'd like to keep this setup as simple as possible.
I've researched more pump options than I care to think about.
I'm not crazy about using a submersible pump inside the storage tank.
Can someone recommend a pump that will deliver the 20GPM at 65PSI. It will sit right next to the tank with zero head and flooded suction.

Can anyone comment on issues with the following configuration?
well pump..>pressure tank...>water tank..>manual float valve

Tank out..>booster pump..>house/irrigation system