Dottymo, absolutely you could do trapunto. In fact that would be the preferable thing to do if quilting on a domestic sewing machine as opposed to a LA. I can't imagine trying to manipulate a double batted quilt around on a DSM. However trapunto involves the extra effort of using water soluble thread and trimming away the excess batting. The results are most definitely worth the effort. It is too bad the OP is allergic to wool because that would most definitely be the way to go without doubling or doing trapunto.
Double batting is best done on a LA and it mimics the effect, like faux trapunto, especially when doing a tight background fill to get the feathers to pop.
It has been my experience that a shiny thread shows the quilting more as does a high contrast thread. But high contrast will also show every wobble and mistake. I like Glide 40 wt poly or Isacord 40 wt poly for that for shiny.
Here is my example. This one had bamboo on bottom and hobbs polydown on top. I did Mctavishing as my tight backfill. I used Glide 40 wt poly thread if I remember correctly.
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