bear viewing in Hyder (AK) Which lens?

next augustus Ill do some bear watching from a boot a the knight inlet and in Hyder alaska. I know in Hyder, there are boardwalks.

I have a 5DmkII + 24-105, 70-200F4IS and 1.4TCII (so max 280mm)

Should I need a longer lens? I don't want to buy the very expensive ones but does a 300F4IS (use also with the tc) add enought worth the 1300 euros?

Anyone experience with bear viewing on the knight inlet or hyder?