TJIs have ply as the center of a wood "I" beam and are damn rigid in that orientation. Lay them flat and they flex more than a dive board!

It sounds workable to me, but there are some engine-ears on here that could run some calcs for you.

If you take the time it takes, it takes less time.
--Pat Parelli

American by birth; Alaskan by choice.
--ironbender