A lot will depend on good genetics, your age and how long you've stretched your skin for.
Unfortunately, no amount of targeted exercise or moisturising products will make much difference.
As for the tummy tuck...
When I had my belly hernia repaired my surgeon kindly slashed some of the loose belly skin off (I had a soccer ball's worth).
It wasn't plastic surgery (his words not mine) - and he certainly was right about that!
It wasn't so much a tummy tuck...more like a slash and rip!
I ended up with a massive scar from one hip to the other; saddle bags of loose skin on the hips - and no belly button!
After 6 months you could still see the scar easily and the distinctly different colours of the skin regions.
My stomach was very weak even after a year - so much so that swimming was uncomfortable.
But now after nearly 3 years, the scar is barely visible (even close up), the skin regions are identical and swimming is comfortable.