Looks awesome! I love the water tote for a sump.
Something you might consider in your plumbing is to suck the water out of the bottom spout of the sump and some way to stir up the bottom while you are doing water changes. Sediment is going to collect in the bottom of the sump. You will probably want some way to turn up the sediment while doing water changes so it all gets sucked out of the system. Maybe a couple powerheads? Maybe a broom stick? Maybe some kind of rubber matt lining the bottom of the sump that can be pulled up a bit to unseat the sediment? I am just throwing some ideas out here to spur some thought.
Flexible PVC pipe is great. It has a low flow resistance and it makes plumbing a lot easier. One of its characteristics though is that it doesn't weld (glue) as easily as regular pvc. I highly recommend sanding the sheen of the flexible pvc pipe where it will be welded and also the female fitting that it is mating to. All PVC fittings should be sanded before welded but flexible PVC even more so! For welding flexible PVC I use a generous amount of primer on the outside of the flexible PVC pipe. Then a generous amount of primer on the inside of the fitting. Then I do the outside of the flexible PVC again with more primer before applying the cement. You really want the flexible PVC to melt to form a good weld! The flexible PVC should still be slightly wet from the primer when you apply the cement.
I had to order clear PVC primer from Amazon. The only primer my local home stores stock is the purple stuff which is required by code for house plumping but you can use what ever you want for Aquarium plumbing. The purple is just a marker so an inspector can see that a weld was properly primed before it was glued.
Are you going to make any additional holes in the sump? If so I highly recommend that you check out Uniseals instead of bulkheads. They are much easier to install, do a great job sealing and allow for a little bit of give and bending while still remaining water tight.
https://www.amazon.com/Natural-Uniseal-Pipe-Tank-Seal/dp/B00TOONO6U/ref=sr_1_5?dchild=1&keywords=uniseal+2"&qid=1622316999&s=hi&sr=1-5
I didn't know that they also make white Uniseals, I have always used the black ones:
https://www.amazon.com/Natural-Unis...1&keywords=uniseal&qid=1622316870&s=hi&sr=1-3