H2ODoctor

Another option is the Cotton Carrier vest.  I use mine for my 7D with 100-400.  I can hike all day with it with no pain.

I am just a few years younger than you.  May I offer my experience.  I seldom use a tripod and so like you, I am interested in having telephoto lenses with IS.  Don't be quick to discount buying...

Don't worry about the weight.  I'm in my sixties and have no problem with carrying a 7d with the 100-400.  I use the cotton carrier vest to take weight off my neck.

Lossen the ring and it will no longer be sticky

Rent the 100-400 instead of the 70-200.