I have the Highfield 310 in Hypalon and Yamaha 15 HP 2-stroke which is far better than my old Zodiac Fastroller 320.
I think a 340 is to big.
It is possible to open the hatch of the shower even if the dinghy is over the hatch. Enough space to use the winches at the mizzenmast.
On passages ( normal sea, not transocean ) the dinghy is fixed to Cooneymarine Oval 15Zero davits with dyneema.
On the aftdeck I use a 50 USD Protection from walmart against the sun.
Wolfgang SY ELISE Amel 54 #162