Please excuse the poor lighting and photo quality. This is about the best I can do with what I have.
I had to mount my reservoir up here in the 5.25" bay (bolted to a mount hole) because there was literally no where else in the case it would fit.
This is about the best lighting I can manage. Here you can actually see where my pump is mounted in the basement, and its related routing.
Because this 60mm thick 140mm radiator wouldn't natively fit on the rear exhaust mount without interfering with the motherboard, I had to offset it from the chassis with these improvised standoffs on every other corner that you see here. I couldn't fit a nut on the end of the bolt to secure it, so the way it's actually secured is shown in the next picture.
To hold the fan+radiator assembly to the chassis against the standoffs I made, I had to use a zip tie on every other corner as seen here. It's quite solid, I just think it's kind of silly what ends I had to go to for this to fit.
My Personal Improvised Machine
After having to do an emergency move flight, and my previous case being too large and heavy to take with me, I took only my hardware itself inside the case. When I was able, I bought a relatively inexpensive case that (on paper) would fit my hardware, but ran into some problems. This case is great for 120mm profile water cooling, but very tight on 140mm. Lets just say I had to do a lot of improvising, with basically what I happened to have on hand. The system now is the result of that improvisation, with incremental revisions behind it.
This is my personal (and only) machine, that has evolved over some time.
All fittings, GPU block and pump are EK, reservoir is from AlphaCool and I think the tubing is PrimoChill. The 140mm radiator in the back is a Hardwarelabs Black Ice GTX. I have a temperature sensor from AlphaCool also mounted in the bottom of the reservoir - fans on the radiator respond to that temperature rather than hardware.