Might be worth a call to the manufacturer, it's possible they might pick up the tab for any mods if they accept that their kit is not fit for purpose.
Worth a try, unless your customer doesn't care about any additional cost.
Reply to the thread, titled "Generator Supply" which is posted in Electrician Talk | All Countries on Electricians Forums.
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc