We do quite a bit of "coastal driving" the other side of the thames to you badboy...but in honestly i wouldnt wade one of my cars in sea water, not for risk of loosing to the tide...but to the certainty of loosing to rust!
The sea is a killer when it comes to cars...my fourtrak used to play on the beach/mud a fair amount, I washed it all down everytime...but the rust, it is terminal. Bear in mind you can only clean some of it...your frame will be full of sea water and rot from the inside out!
Wade a car in the sea...definatley sell it very soon afterwards foggers...
To do a run like that above, I would club together and buy a barely legal fronty for a go...and then break it for spares on ebay after to recoup the cost!
Just a thought anyway guys...
If you look on a map we have done warden bay/leysdown to minster on the else of sheppey, down the beach, cliffs mud etc loads of times and it is cool, but needs local knowledge or can be very dangerous!
Sometimes stop overnight halfway in the middle of nowhere and have bbq, and a bit of fishing.
Can be a mission if something goes wrong though, my mate did his clutch in an SJ and ended up doing 3 miles of cliff climbing and rock crawling with him in tow in my landcruiser. Ripped the tank out of mine..drove the last mile running on a 2 litre coke bottle full of diesel cable tied to the battery!
My "get out of jail free card" was we know most of the farmers with land at the top of the cliffs, so worst case can borrow a tractor and an emense length tow to get out if really screwed!