Less is more.
Since your RTL dongle has a built in bias tee, use that. You could make your own LNA very easily with a piece of RF trace and an x-acto knife. For satellite reception you really want a low NF. A NF over 1db may work fine, but its not optimal. Since you can get a device thats better for very little and its easy, and your dongle already has a bias tee, why not try doing that?
Find an discarded RF PCB with some 50 ohm trace on it - preferably one with two SMAs on it but thats not really necessary, you can solder some coax to it. Get a MMIC like either of the aforementioned ones, (I would try to find a PSA4-5043+) and a decent quality ceramic capacitor of an appropriate value for your DC block.
200 pf is fine, you can use one up to 1000 pf if you want or as little as 100 pf. I would use a 200 pf one to start.
Cut the trace twice, with one of the cuts being around (like right on top of) vias on both sides. (the GROUNDING on both sides being short is the most important thing to get right here) and put the capacitor across the first one and the MMIC input to the capacitor side of the trace and the output/power in on the other side. Don't just ground the appropriate places to the ground plane well, be obsessive about getting it close and short. Be careful not to heat it up for too long. be gentle with the legs especially when its hot, you don't want the chip to melt and a leg to come off. Also do your work over a tray under bright lighting so you don't accidentally lose your chip. Its easy to do.
There are lots of MMICs that could work here, however when I decided to build a LNA I did a parametric search of all of the ones I could find and decided on that one for a number of reasons. It still seems like the best all around choice for something like this to me. Depending on how you mount it, it may make more sense to dead bug it. That means mount a chip upside down with its legs in the air. I would then use a small piece of copper to connect the two ground legs. Flat copper is better than wire because less inductance to ground.
Whatever connection method you use try to keep it as short and consistent as possible. Chances are in your junk box you have some old RF something that has an appropriate trace you can chop off. Old wireless cards, for example can often yield several useful small chunks of RF trace bearing PCB with vias and everything all ready to go.
Solder the antenna end coax to the end of the trace with the DC block cap and the trace leaving the other side of the chip to the coax and the braid going to the receiver and its bias tee to the other "output" end. You're now done. Don't forget to test it with your ohmmeter before you apply power. The datasheets will give you a good idea of what you should expect as far as current draw. If the current draw is higher, or lower, remove power and check for a short or open.
Then see how well it works right at your antenna with you sending your power to it from inside. It it works well, figure out a way to weatherproof it.
The LNA you got may be great or it may be crap, but either way, the nice machined box it came in, with voltage regulator, etc, appears to be nice enough to be worth what you spent.
Also, if you wanted to replace the MMIC in it it looks like it would likely be easy.
Others here probably could evaluate it's strengths and weaknesses better than I.
How does it work so far for you with an external supply? Make sure you supply the right voltage.