If the concensus is that airlines are starting to more
seriously enforce the 62" limit then I'll shop around for a large golf bag
to replace the duffle bag I currently use to carry my kayak.

Yes, without a doubt, the airlines are vigorously enforcing the 62"
size and the weight limits. Some airlines have now lowered the weight
limit from the previous 70 pounds to 50 pounds (United, for example,
has a 50# limit). It's all because of their new "maximize profits at
the expense of customer service" effort.

I've never flown with a collapsible boat, but do fly with a tandem
bicycle, which is designed to fit into two 62" cases. But, it's a
challenge to keep it and all the necessary extras under 50 pounds per
case (when you figure that the case itself weighs 15-20#). Many
airlines' rule of carriage specifically single out boats (and bikes)
as requiring an extra charge. Theoretically, they could charge me for
my bike, even though it's in a regular-sized suitcase and under
weight.

Golfers and skiers get an exemption, for some reason. Most likely
because they are a large customer base for the airlines, and would not
put up with extra charges. Bikers and paddlers are not, as much as we
might like to think we are.