This setup is calling out DIY to me lol.
One idea might be to make your own canister filter. Since you already have a sump you could use it for a DIY canister filter! I love making these, it just saves you a TON of money, and you can really make them just as good as these XP's, and Ehiem's. I made a DIY canister filter for my 55 gallon African Cichlid tank. All I did was take a 5 or 10 gallon bucket (make sure it comes with a locking lid (like a butter container), cut a hole slightly smaller than the size of the tubes/hoses you are going to use on the side of the bucket approx one inch from the bottom, this is going to be your inlet. After you get the hose through the hole (use pliars for a tight, hopefully airtight fit) you need to seal the outside of the bucket around the hose ( you can use silicone or any other sealing product such as calk or whatever you can find). Then you would want to use something to set ontop of the hose inside the bucket so when you start piling filter floss, ceramic, or anything else you are going to use in the filter, it doesn't pinch the inlet hose or break the seal. Chicken wire or eggcrate (light diffusers at home depot or lowes) work great. After this the customization gets pretty endless, you could just stuff it full of filter floss and/or sponges, peat, ceramic, or whatever you need depending on your water properties. Just seperate each section with a layer of egg crate or chicken wire.
Example: / = a layer of egg crate or chicken wire
inlet / coarse filter floss or foam / peat / ceramic rings / Fine filter floss or foam / outlet
After you get that all setup its time to put the lid on and make this work! Before it will work you will have to cut a hole in the lid slightly smaller than the hose, pull it through about a 1-2 inches. After you do that seal the top of the lid again as you did the hole on the side. Once this is complete you have your DIY canister filter. All you would have to do to get it working is hook the inlet up to your sump so the sump pumps water to the inlet tube, into the filter and then have the outlet hose run back to the tank. You could easily make this for less than $50 which is about 1/3 to 1/8 the price of these nice high-end canister filters and it does the exact same thing!!!
Before hooking it up to the tank, after you make all the holes, insert the tubing and seal them, before putting any materials in the bucket, take the bucket outside, make sure the lid is closed and turn your hose on. Shove the hose in/around the inlet tube so the bucket fills up. Once the water fills the entire volume of the bucket, the water will have no where else to go but out the outlet tube on the lid. This is just a test to make sure its water tight.
I have built approximatly 3 of these, two with different size butter containers for my smaller planted tanks (10 gal, and 20 gal long), and one using a 10 gallon bucket with a lid for my 55 gal African Cichlid Tank.
If I have some time one day, Ill post a how-to in the DIY forum with some pics.
I hope this helps!