My 2010 was actually worse than that with a rusty tailgate as well. I've just had it all sorted at my local bodyshop and had the sills rustproofed while they were at it.

There was quite a bit of surface rust behind the wheelarch liner as well which was quite surprising.

Mine has no towbar so has certainly never been used for boat launching. As mentioned previously, if you catch it early then it's easy enough to resolve. 2010 4.4 TDV8 Vogue SE