I have a 2019 FT. I have a torc ground anchor from pragmasis and then I put a DIB D-lock round the swing arm and attach a 19mm pragmasis protector chain. I then have another chain and lock through the front wheel to the same ground anchor. Finally, I have a BikeTrac tracker fitted. Belt and braces approach needed in London!
I think the safest spot to run a chain through is the rear part of the frame that comes down from below the back of the tank. You'd have to remove the engine to avoid cutting the chain...
Mostly though, I used to loop around the swingarm. Remember reading a while back that one of the most difficult security devices to cut off was a disc lock on the rear rotor.
Rear wheel and disk takes more time to get off than the front.