I think that should be enough, but you should consider more important than the amount of line is the quality of the drag system you have on your reel.
A good sized laker will find the flaws of your drag system in a hurry, not to mention if you are going to specifically target Lake Trout.
Repeated battles with multiple lakers in a day will give a reel a pretty good work out.
Buy good quality equipment.
If I were you I would P.M. a guy like drifter to see what he uses. He gets huge lakers every year, and lots of 'em.
Hope this helps,
Wiener