Forget inflatables unless it's the only option.. eg storage and transport reasons.
The 12'x34" Naish Crosover is a good inflatable to concider..
www.naishsurfing.com/product/glide-crossover-inflatable-120-x34-lt/You need big.. Going slightly too small would be a huge mistake.. btw how heavy are you?
One board that comes to mind that would be perfect is an 11'2"x 32" Naish Mana.
www.naishsurfing.com/product/mana-112-gsx/I have the same board from from a couple of years ago and it was called the Quest back then.. It paddles and windsurfs great.
Another great board worth concidering is the new LT Windsurfer One Design.. It's a windsurfer that also paddles great.
I have one and it's similar dimensions but slightly narrower at 30" wide than the Naish board that is 32" wide. It works great as a SUP board.
This is a vid that I did showing my 11'2"x 32" Quest..
This is another vid that I did windsurfing the 10'10"x 31" Naish Nalu. It's another good option..
www.naishsurfing.com/product/nalu-1010-gtw/