i reckon your best option is to replace the suppot panel with a fresh one, ive done it with a 31 sedan and its not that difficult, once i had drilled thru the spot welds i was able to pull the inner skirts forward to where they used to be,the support panel cost me around $450 from nissan which was a better option for me than using a secondhand one
i rang a mobile welder to weld the thing on to the car(all work done in my backyard)