Room and Board's Parsons bed has a trundle option, I believe; that may be a well-built bed. I'm looking at beds too.
Charles P Rogers also may be worth considering for trundles; my first pick was a yellow Hamilton bed from Schoolhouse Electric, which reminds my addled brain of Van Gogh's bed. Not a trundle, though.
My other notes from this forum are to consider the Case Study bed, and also Dixie Foam mattresses.
I'm sorry I couldn't help more.
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