sorry for your problems…
I have often recommended the Kumho 195 to replace a 205 sized tire because it more closely matches the physical size of the OE tire and it unlike the Kumho 205 isn’t made in china… and yes Kumho in china has had quality problems of major proportions… so much for the place of origin doesn’t matter…
I have used the UE168 on a van (not a trailer) and wasn’t impressed with it but it didn’t fail either… I have been impressed with the M8008 in my research for my own trailer tire replacements… the problem is I only researched the 225x75x15 with the mfg. themselves and has you now realize tires of the same brand may have different quality levels for different sizes…
Based on my study in general and faced with your decision, without making a recommendation, I would be comfortable with and give the edge to the M8008…