Hi Barry,
No sweat in the sun, just use the sunny and F16 rule of thumb (or maybe sunny and F11 rule which works better for me locally) and ignore the meter reading.
EI 400 (Tri X) at F16 (F11 for me) = 1/400 shutter.
What you lose is the ability to narrow the depth of field with aperature. If you need larger apertures you'll need a slower EI film or the ND filter.
A great alternative to ND filters are red and orange filters. They pump the contrast up (make the sky darker and clouds brighter), you will need to add a filter factor to the F16 rule but that's easy.
BTW, the snow scene may fool a meter but will not fool the film, it tricks reflective meters into thinking it's too bright out and generally asks for an underexposure.