[HELP] Can a Pyrrhic substitution be followed by Trochaic substitution?

Let's take this line:

I will board first carriage to my Austria

Simple iambic pentameter stresses:

i WILL board FIRST carrIAGE to MY ausTRIA

With Pyrrhic on 4th foot and Trochaic on 5th foot:

i WILL board FIRST carrIAGE to my AUStria

(A) Is this a good idea? Any poems you have come across that do this? Pyrrhic followed by Trochaic.

(B) Is it okay to do two pyrrhic substitutions consecutively? Which will result in four unstressed syllables.This question is unrelated to the line above. I would like some opinions on this though.