My rather smaller scale experience may not be relevant (?).
With my 14 ft Storm Petrel, I launched from the road trailer - the Swallowboats way (they were called that way back then), which no-one seemed to question, so why should I? It was usually a pain: as the weight of the boat didn't merit faffing about with the car, I was effectively using the trailer as a (rather heavy) trolley. It was nearly always obvious that going further into the water would make launch/recovery VERY much easier, but I didn't because of those dratted bearings.
For my 12 ft Trouper I was determined to go combi and have not regretted it under any circumstances I have met with. I'm usually launching/recovering solo. I can usually float the boat onto the trolley. I have two jockey wheel arrangements for the trolley, one with a useful longish handle, and the other without. Slipping the trolley onto the road base has never been a problem.
For a boat the size of mine, it really is a no-brainer. I appreciate that 17ft is quite a bit bigger. I think your idea of a simple tow hitch on the trolley would mean you could tow most (if not quite all) the way out with the car, and I really do think using a trolley makes life SOOO much easier. I would go for it.
Michael R (Trouper 12 'Cavatina')