I have the Eshopps Eclipse in size medium on my 72 G. My tank is also bordered, and I placed the top of the internal weir snug against the plastic trim along the top of the tank, for the same concerns.
I'm running a 1" ID reinforced nylon hose with a Two Little Fishies ball valve to regulate flow on the primary overflow drain. The emergency drain is a the same type of hose, without a valve, just straight to the sump.
With a Jebao / Jecod DCS3000 return pump, the water level has not dropped below the plastic trim on the lowest power setting. At full power, it has not overflowed, or come close to overflowing. This product is fairly well thought out for us plastic trim tank owners.
I feel that overtime, a person will need to clean off some of the growth on the weir teeth. For me so far, it has not been an issue. If for some reason a person was not able to, the water would just flow over the top and into the overflow... There would never be a flood, because there is no lid... I'd suggest a strainer be placed on main drain 1" bulkhead to keep critters out. My Valentini did jump out of the tank and it was found immediately below the overflow box... There is nothing stopping these guys from jumping over the weir and into the overflow box. I'd rather hear the emergency drain slurping air than fishing out my hoses.
One more thought... The main drain will funnel like crazy. I have not yet tried this, but I came across a thread where a guy placed a 45" elbow in the 1.5" drilled bulkhead to divert flow towards the emergency pipe. This stopped the whirlpool effect for him, and he's not running a strainer.