If you can, check to make sure the insulation in the walls or in the attic is not the type that is faced with aluminium foil. Also check to see that the vapor barrier isn't aluminium. That can really detune your antenna and/or capacitivly couple all your signal to ground. (Had it happen to me once in a rented house, I simply could not radiate any signal at all on 80M - The dipole was up against the house hidden in the wood siding, of course right next to the giant sheets of aluminium foil.)
Otherwise, as mentioned before, your wooden structure is invisible to HF. And, it is fun to operate stealth.. It's a challenge. Not only do you learn antenna theory, you will learn about camoflage and hiding in plain site.
For example, I once told my landlord that I was a bird lover and got permission in install a birdhouse on a 10' copper pipe in the back yard. Amazingly, if you lay small gauge black stranded wire in the grass, it disappears.. Best of all, the whole thing tuned up and worked decently from 20M - 6M.. An RF miracle!!!!
In my experiences with stealth operating, they key has been to get as much wire up as practical - get as close to the size of a full length dipole as possible. You can then bend it up as necessary to fit the allowed space. Bends should preferably be near the far ends of the wire.
Just get something up and experiment, you can get a decent signal out by making and hiding your own wire antenna creations.. A compromise antenna is far better that no antenna at all.
Just remember that creativity and an antenna matching unit (tuner) will be your best friends.
73!
Bill AB9TA