I had already started with the shims so I just went with them. I got it really level and filled all of the gaps where I could get one in. Turns out that it wasn't that difficult to trim them. I just took a carpet knife and scored the thicker pieces really well and then they broke off nice and clean. The thinner ones I could actually cut right through with a few passes. So it wasn't too bad. I als picked up some oak "shoe" trim for around the bottom.
The CL and returns are all working really well. However, I did come up with one problem. When I shut everything down and the sump fills up to it's max height, it causes the uniseals between my fuge & sump to drip about 4 drops per minute.
My darn drill has a bent shaft (I dropped it off a ladder and it landed just right). So when I was drilling the holes for the uniseals, I think the hole saw was wobbling enough to get slightly oversized. So either the addded head pressure or the added deformation of the tub walls creates a slight drip there.
It's fine when everything is running though.
So I'm filling my tank with the garden hose and it has a little ball valve on the end of it. The restriction causes the water to come out pretty fast. The hose comes out of the tank for just a second and scores a direct hit on the window curtains

but the wife was not home and it is all dry now
So back to the sump/fuge drip, I think I'm going to have to use bulkheads there. The thing is, I'll have to use two bulkheads with a "close nipple" between them. I don't know of a bulkhead that is made to seal from both sides.
If anyone knows of a bulkhead that can seal both sides, I'd love to hear about it. I think the uniseals would have been fine if the holes were not drilled oversized...
Maybe I should bite the bullet and get a real acrylic sump. But I think I'd still need a two piece in order to get the thing in and out of the stand. So I'd still need the whole bulkhead thing.