If you're looking to downsize, I'd say run one sub in a 1.5-2² @ 35Hz.
45Hz is pretty high for a daily driver. Better yet, build the port to 30Hz (long) then test it. If it's hits too low, shorten the port a bit and test again.
:word: I'm currently running a similar setup. This amp put outs between 420-500 watts @ 2ohms, sub is a Skar VVX10 (600 RMS)
This was right after we finished putting it all back together after the build. I have an MB Quart 1.1500D on order, should have it next week. Box is 1.5 cubes, tuned to 34hz with an aero port. (popped off the inside flare which shortened it a couple inches to raise the tuning closer to 37-38Hz, I like it better here for rock/alternative) It definitely pounds, but it is quite musical too.
In progress pic before port was installed.
Ultimately the box will be finished in black, but one step at a time.