many folks will tell you that check valves all fail - mine hasn't yet and I use it every day at feeding time.
What you should plan on is for your system to be able to withstand a failure that would draw back into your sump and still not allow flooding. In my case, I have about 12 gallons free in my sump, which could handle a stuck float switch that would drain my ATO, a bulkhead failure which would drain my overflow, and a check valve failure, which would suck through my return plumbing until the siphon broke.
In your case - none of that applies because you would be draining your tank, and killing everything in it. When I have seen such types of returns, they were for closed loops, so not siphonable, unless there was a large leak, in which case you are sol anyways.
See if you can work your return over the back instead and maybe add a small closed loop in the rockwork. The good news is that since you are going acrylic you can drill anywhere.
jp