I don't have much experience on this topic, but you probably right. Friend of mine had the same status as your( medical has been recieved) in first stage and he got approved within four months from singapore which is superfast. Hope it happens for you. I dont want anyone goes through same situation as some of us going through( interview letter without date). To answer your another question about TRV , which is very good idea, and has no negative impact on your other file. Make sure you provide enough proof and other supporting documents that he will go back and no intention to stay here illegally. Chance is slim but you never know unless you try. Wish you good luck
, I hope Mirjahan will give expert opinion on that ,but i just wanted to share my experience if it helps.