Are 5 AP classes too much for Junior Year on top of ECs?

I had a similar schedule (four APs, officer of four clubs, varsity lacrosse, some other stuff…) and I was able to do it and get all As.
I took Physics, Calc, Chem, and Lang.

It’s only a matter of your time management skills. It’s definitely not impossible (or even that difficult) to do, but you’ll have to be organized.