Merino t-shirts are fine in warm weather. I see Minus33 sells theirs in XXL and 81% of Amazon reviewers report it fits as expected. Icebreaker shirts are a bit more expensive but more well-known. They also come in XXL.
Are you saying that in addition to the pants you're wearing you take three pairs of Levi's jeans with you? Merino wool isn't really a pant material, but there are travel jeans that pack down smaller and dry faster than ordinary jeans. Pack no more than one pair of pants (in addition to what you wear on the plane).
As for the socks, 6 pairs is more than you need anyway. Merino socks can dry overnight—certainly in 24 hours. You really only need 3 pairs (although you could get by on 2 or even 1 if you washed every night). Expect to pay about $15-20 per pair. Darn Tough are regarded as the best brand.