A friend of mine in Northern Germany is building the boat linked to below. He is going with a torquedo as well. If you dig deep into his blog you'll the very nifty way he is making it retractable.
https://janvonderbank.wordpress.com/eine-seite/?fbclid=IwAR3GhP5emTx7t5NGetCmOkSsKWqNIl0EU9DmISL9TuEmYjp4wLFYdfRU2Rc