Heavy Ps Use and Portability do not play well together, period. Any successful mix will be a compromise.
I'm a heavy Ps user. My day job involved using Ps to edit large image files for an art photographer. I frequently work with files too large for the old PSD format in pixel count and/or file size on disk and have to use PSB Large Document format to do my work. For me, efficient Ps work requires (in order):
- mouse, not a trackpad
- at least a 27" monitor
- full sized keyboard with numeric keypad
- fast SSD drives
- as much RAM as I can get
- fastest i7 that I can get
I'm currently stuck working remotely because of my wife's medical issues. I find using my little MS Surface Go with an external full keyboard and 27" second monitor and an older PS CS4 much more functional than any 15" notebook without externals. Reliable use of easy keyboard shortcuts (full keyboard), precise cursor positioning (mouse), and good visibility (large monitor) and critical to efficient work.