I am a bit confused here ChrisF ? are you also building a boat with the Z drive as I assumed this was Newby7's build blog??
The bellows should be ok even though as you say the rods move lateraly, but you could spin the servo 180 degrees and reduce the lateral movement there would be enough room in the bellows for that.
I saw the B-M site and the z drive looks like the anti cavitation plate is a bit short to fix a pickup tube, but I myself would fit a piece of carbon fibre plate on to hold that and fit to the top ofit and shape it sa as not to look just like a bad add on.
I have a couple of hulls, one Fibreglass Huntsman hull with just the deck already fitted. That came from Anglia Model Centre a few years back but with no superstructure. I will design my own when I make it up. Also an MFA Spearfish still in the box, I think it would look quite neat on that or even the old Areokits Sea Commander that I have got for a refurb.
I even have an unbuilt Stratos Hydrofibre Interceptor that I bought back in the 80's which all I done to that was to start to fit some holes on the decking for some stantions and then put it back in the box. so I do have a few options.
I am going to thin out ny boats, I'm selling off 2 RAF Crash Tenders a 46" Vintage model boat company remake and a Genuine Aerokits 34" that I bought back in 1994 when they advertised in the Model Boats mag. It was advertised as 50 kits for the 50th anniversary of the boat.
I sold the Graupner Z drive as it was so heavy and decided that I didn't like the look of it☹️.