For most people a quarantine tank would be far more effective.
Actually, let me rephrase that...For people with self control a quarantine tank would be far more effective. I got rid of my quarantine tank after I finally managed to sell the last of some 300+ bristlenoses out of it...
But then, I've only been keeping fish for about 10 years, last year I finally threw out a lot of old rubbish and I counted 4 fluval 404s whose motors had failed. All but one bought new. And their impellers were getting nearly impossible to buy, which they seemed to need replaced every year or two. I've been running 3 CF1200s for about 3 years and they've needed nothing more than cleaning. So far looking more reliable than 404s at least.
First you're wanting to keep koi and wanting to know if anyone has any, then catfish, rudd and gambusia...Clearly you are a fan of large fines and jailtime. Would you also like some P? How about a stolen TV?
I don't think I'd worry about it for a small tank like that if it's actually 5mm overhang. The thickness of the glass should be more than that. It wouldn't hurt just as a bit of extra insurance getting a piece of plywood made up to match the tank bottom, but it's not really necessary.
Also, the tank sinking into the wood is not an issue. Not unless it's made of soft balsa that you can crush with your fingers. The pressure over that area will be small. It's any high points concentrating pressure on the base and breaking it you need to worry about. Floor underlay may do the job, but the standard is a sheet of polystyrene foam.
How would you shorten my name?
There are a lot of unfortunate combinations that you know the parents had to have noticed. The worst names I've ever seen are "Dick Butkis" and a "Richard Asramer"
I've seen a couple cool names though, first that comes to mind is "Forrest Whacker"
Wouldn't want a dangerous introduced predatory species like the salmon mucking up the dangerous introduced predatory species that they can charge money for like trout...
I just started considering timers a wear item. I never managed to find one that lasted more than about 4-6 months before failing running MHs. But with the such a small load on them I'd just go for the cheapest, never had a problem with a timer outside of running MHs.
Are there even any salmon in the country? There are landlocked populations all over the world that would probably work if you had the right setup, but I doubt doc would be happy with you trying to bring them in.