If you want to attach something to something else, especially if it has a flat/smooth surface, without using bolts or screws, consider using Very High Bond tape, or Dual Lock fasteners.
3M VHB tape is used to tape auto panels to cars, and skyscraper glass to buildings, so should work for your purposes:
https://www.amazon.com/3M-Tape-5952-Multiple-Sizes/dp/B01EOEW25S
If you want to be able to remove the thing without damaging the hull or item, you may want to tape an aluminum/plexiglass mount, to which you bolt the item.
3M Dual Lock:
http://www.andybaird.com/travels/gertie/superlock.htm
3M VHB tape is used to tape auto panels to cars, and skyscraper glass to buildings, so should work for your purposes:
https://www.amazon.com/3M-Tape-5952-Multiple-Sizes/dp/B01EOEW25S
If you want to be able to remove the thing without damaging the hull or item, you may want to tape an aluminum/plexiglass mount, to which you bolt the item.
3M Dual Lock:
http://www.andybaird.com/travels/gertie/superlock.htm