I ended up using Americh, which are available in solid acrylic. Although I did a shower base, it's essentially the same thing, just deeper.
Go here: http://americh.com/products.php
Go to Bath Tubs and put in the shape you want, and then the size you want.
Many of the models are available as just tubs without whirlpool jets. You absolutely must specify a 'tile lip' and whichever one you choose.
Did my post about your Hansgrohe unit help at all?