I would love to have a 1,000gal+ setup for my monsters. I've seen how much my 2 pacu like schooling together and would like to take in more as rescues. I was thinking of digging an outdoor pond and building a greenhouse to keep the temp up year round.
It is definitely doable. Utah is a little vague as there are some pretty cold places in Utah. If you are in a cooler area I would recommend using twin wall panes to insulate better. You can heat the building as well if you need to. An evaporative cooler will make the building much more hospitable in the summer. I assume this is a place you are going to want to sit and relax.
If you really get into schooling fish like this I like red hooks. If you have ever seen a school of 7-9" red hooks they are awesome. If I remember right the Cleveland aquarium had a good display. While pacu are great fish 1000 gallons is going to get snug with a few 30" pacu cruising around. I have always wanted to keep the pink pacu.