IMO It's gonna be pretty hard to seal a funnel to the bottom and not have it leak but I could be wrong. You can get the drain fittings for an HRV from a HVAC supplier that are only about an 1/8" thick. Google Lifebreath drain fitting kit, I use them as overflows in my trays and they work ok. No matter what you do you will get a bit of standing water unless you buy a proper flood tray. Good luck! Great to see a fellow DIY'er solving issues

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