Can anyone tell me how long the rear springs last on a 2001 Supercrew?

I notice that mine seem to be bottoming out when loaded for camping and trailer towing. I have 66,000 kilometers on my truck. Had all the shocks replaced last summer. Can I have helper springs installed or is that a good idea? I have the 4.6 litre engine with the trailer package.

Any help would be appreciated.

 

No idea, my '01s rear springs seem to be pretty good still, surprizingly since my undercarriage is rust owned