This is my opinion and should not be confused with what the expert flyers may have to offer. I have flown a dozen of these in the past 25 years and I really never worried to much about the plane being nose heavy. I flew with Enya 35,s and K&B 35 series 75 in slow combat and even had one I flew in profile carrier. The tank on the inboard side should work OK. I always used Veco profile tanks ,outboard. I have seen clunk tanks used on CL models and they worked OK. The only muffler I ever used was a DuBro stack with the spring in it. Not much of a muffler but passed the test. I still have a Streak with an Enya 35 that I fly when the grandkids show up. Lots of fun and its only 8 or so years old. To bad Top flite quit kitting it.
I hope you have good luck and enjoy it as much as I have.