Homebrew PCBs

Hi all,  I am building a tube guitar amp PCB.  It requires heavy
copper on thick boards.  I would like to use 1/8" boards, but cannot
find any locally.  Anyways, here are my plans:

Toner transfer method using Phoenix TTS paper (all I can get here in
Canada).  Then I plan to etch using MG Chemicals Sodium Persulphate
and hand agitation.

Is this reasonable for this thick of copper, or should I try a
different method.  Any hints, tips, or related sites would be appreciated!

thanks
Don