Of course it's probably best to have someone with a background in home construction check everything out, it's kinda hard for anyone off the cuff to say you are ok or not (using the "playing it safe" card
One think i can add is, i think the orientation of your flooring joists are running the wrong way if anything, regarding the tank placement. Correct me if i'm wrong, but i think the best way (when at all possible) is to have the joists running the other way to give you more spread out support with more than with a few.
Just looked in my basement(but i already knew) and have to admit my 180 is placed near the outer wall with joists running parallel with it
And my 75 is placed in what i would say is the "correct" way with the joists. And FWIW, both tanks jostle a lil bit with foot traffic regardless.
Bottom line, i'd say get someone who's in the business, or at least knowledgable enuf to take a peek at your joints to get a better determination on if things will work out for you.
15 yrs with both tanks in this house, the prev house i had shored up the 180 underneath w/ jackposts, just cuz (and it was with the joists running the "right" way )
Prob not a real answer to your question, just my