Okay. What would be entailed by those options? As in, all of the vowels would have a long and short version, or none would have them?


Hm. I'll make an edited list with the vowels fixed, but here's some sounds:
xlt-/xɔlt/-like "cult" with a west-coast accent.
Lots of other words will have [cons.]lt endings, as -lt is a conjugation. most conjugations have a -l[consonant] ending, and they usually have the /ɔ/ as the sound in between.

I've gone through some of the options already. You could still have quality contrasts, but these would be the surface realisations of underlying contrasts in quantity. (E.g., /iː/ and /i/ realised respectively as [ i] and [ɪ].)

Keep in mind that phonemes are merely abstractions. In English, I've seen the vowel of go phonemecised as /o/, /oː/, /ow/, and /oʊ/. It doesn't really matter which one you use as long as it's consistent with your overall analysis of the vowel system. One reason to prefer /oː/, for instance, is that there are some dialects where this sound really is [oː] whereas other realisations--such as RP [əʊ] or the [ɵʊ] found in many North American varieties--clearly developed from this. On the other hand, using /ow/ makes it easier to write rules about which vowels appear where (such as before /r/). There's no single optimal solution.

If you want to have length as a contrastive component of your vowel system, it should probably be there for most if not all vowels. But you don't need to have a phonemic length contrast in order to have phonetically long vowels. You could still have both [æ] and [æː], just not in the same positions. (For instance, [æː] appears before a single consonant and [æ] when the syllable ends in more than one.)


I'm not sure what you mean by "West Coast accent". In most of Southern California, for instance, /ʌ/ (the vowel of "cult") is being shifted towards [ɛ]. (A feature of the so-called California vowel shift.) A shift toward [ɔ], on the other hand, is characteristic of the completely distinct and incompatible Northern Cities shift.

I live in Oregon, so the Pacific-Northwestish.

This looks like a fun conlang. I hope you are having fun developing it!

From what I know of that accent, your /ʌ/ is pretty close to cardinal [ʌ]--not backed and rounded like it is in the Northeast (and increasingly where I live as well) or fronted as it is in Southern California.

It could still be a rule of your language that /ʌ/ is pronounced like [ɔ] in the ending /ʌlt/. In fact, it's precisely that sort of rule that lends versimilitude to a conlang.