Breakdown of من لباسها را تا حد امکان در کیف مسافرتی میچپانم.
من
I
کیفkif
bag
لباسlebâs
dress / clothes
درdar
in
Questions & Answers about من لباسها را تا حد امکان در کیف مسافرتی میچپانم.
How exactly does تا حد امکان translate literally, and is its placement fixed?
Literally, it means "up to the limit of possibility" (تا = until/up to, حد = limit, امکان = possibility). As an adverbial phrase, its placement is quite flexible. While placed before the destination (در کیف مسافرتی) here, you could also put it right before the verb: ...در کیف مسافرتی تا حد امکان میچپانم. Both sound completely natural.
If I wanted to use the alternative تا جایی که ممکن است (to the extent that is possible), how would that change the sentence?
You can swap it in exactly where تا حد امکان is right now. Since تا جایی که ممکن است contains a full mini-clause (with its own verb, است), it makes the sentence a bit longer, but the meaning remains identical: من لباسها را تا جایی که ممکن است در کیف مسافرتی میچپانم.
What is the infinitive of میچپانم, and would I use this for normal packing?
The infinitive is چپاندن (chapândan), meaning "to cram" or "to stuff." It implies using physical force to fit things into a tight space. For normal, neat suitcase packing, you wouldn't use this; instead, you would use جمع کردن (to gather/pack) or بستن (to close/pack, as in چمدان بستن).
Why does مسافرتی end with a ی instead of just using the noun for travel (مسافرت)?
Adding the ی suffix turns the noun (travel) into an adjective meaning "travel-related" or "intended for travel." So, describes the of bag (a travel bag). If you just said , it would technically mean "the bag of the journey," sounding like a bag belonging to one specific trip rather than a category of luggage.