no kidding. So he take a taxi to the ferry, ferry to Donsak, shuttle to the Surat airport, fly to KL, taxi to stay overnite at airport hotel, fly back to Surat , shuttle to Donsak, ferry to Samui, taxi home.... 'just take a cheap flight'.
Fear owns you mate. I don’t share your fears. You are a slave to it.
For us, global immigration has always been easy. We are mixed nationality couple with 3 residencies in countries that are not our own. Thailand has very flexible rules. You need to know where to go, who to talk to and when.
You obviously have no experience with Thai immigration other than doing what your wife tells you. If i was married to a Thai lady, your route is good. But you clearly have no relevant. experience in the real world.