Finish for wainscot and trim?

[Manalto]

Next week I'll install beadboard wainscot and window trim in the sleeping porch. It's all new wood which is pretty clear of knots, but nothing exotic - just regular lumberyard pine.

I plan to keep the wood unpainted but would like to seal it with something that will hold up in the high humidity of this region of the US. Window sills are part of this so UV protection is a consideration, although the room only gets early morning sun. I was planning to use spar varnish but wonder if that is overkill or tricky to work with. A subtle amber tint to the finish would be nice. Suggestions are invited and welcome!

[Gothichome]

James, my thoughts, go with a tinted shellac on the wainscoting only down side I can think of is the sill. A tinted velspar finish should make sense although I always have images in my head of it flaking off making a blotchy mess.