LOL, I weigh around 200lbs at the best of times and I did a 1000km tour last year on a 32 spoke radial wheel, I put front racks on my bike and most of the heavy stuff up in the front. I'd reckon 20-30 lbs at the very least but likely more since I don't own anything light weight. Tent and sleeping bag went on the rear. Consider also that most of the rider's weight is on the back wheel. I rode this wheel for 3 full seasons and thousands of klicks without any trouble. It's just a generic (likely alex) rim on a specialized branded hub with normal cup and cone bearings. Mind you, this was also on an aluminium bike (another no-no for some) and that was actually a busted frame that I made a carbon fibre cast for... so I have a long history of doing things that aren't recommended.
How does a radial front wheel fail catastrophically? One spoke breaks and all the other ones just come untensioned and then the rim says "yeah, me too!" and just tears itself apart? I think there is a bit of FUD around radial spoking. I'm not saying it should be used on drive wheels or disc brakes, but given the shear amount of abuse I have put my own wheel through, I just can't see it being a problem for a lighter rider with a small load.
If you're prone to worrying you could put green loctite into the spoke nipples. It's important to get the green stuff as it's designed to seep into fasteners that are already done up. It's also not as strong as the blue or red, which also has the benefit of preventing corrosion so the wheel will be serviceable in the future. Before anyone jumps on me the loctite isn't to hold the wheel together or anything like that, it's just way easier than taking the wheel apart and putting anti-seize on the threads.