Where are you going ??? What breed of trout ?
Fish your lake like you would a stream if you don't have a depthfinder. Cast your spinners out reel back vary speed , try a cast and count down a bit to get it deeper. Yes to your crawlers and salmon egg question , slip bobber a try on depth for a while then drop it deeper or bring it up play around with it till you get bit. I would also try some casting spoons like Thomas , little cleo , phobe.
Good luck let us know how you make out.
If your set up for trolling that would take some time to answer so tell us what your boat is set-up to do.
I've only fished for trout in creeks and streams but this weekend I'm going to a lake with trout in it. What can you use in a lake just spinners? If i wanted to use night crawlers or salmon eggs would that be possible and how? With a bobber? Any input would be helpful.