AV Bays in Short-n-Fat Rockets

[RainierWolfcastle]

My current build is a PML Pterodactyl Jr, a nice stumpy little rocket with very long fins which probably does not lend itself to adding electronics...

...so I've decided to have a crack at adding electronics. After a bit of gazing at the ceiling and making a few scribbles I came up with a couple of possibilities.

Option 1 would be a coupler and add an extra section of body tube to stretch it but that kind of ruins the look

Option 2 would be fit something in the nose cone, would have to run a wire down and under the chute to get the charge on the right side? Not sure about keeping the piston with that setup.

Option 3 is make a donut shaped bay to slide in that would still allow a hollow space for longer motors or motor eject charge and still fits under the piston. Needs o-rings both ends to keep out ejection charge, has to be slid all the way inside body tube each flight, needs threaded retainers from bottom to hold it it, along with probably a dozen more issues I haven't even thought of yet.

Number 3 sounds like the hardest so I've started with that one. After doing a quick model I see a few concerns. Space is at a premium, probably going to have to remove the stock eye from the nose and make a bulk plate to allow another inch or so of hollow room. Bigger issue is the vent holes end up a fair way back from the leading edge of the fins, although forward of the 2nd 'real' leading edge. Currently have an eggtimer quantum, by keeping the space for motor eject I can do a test flight and see what the baro results are with the altimeter along just as a passenger? A Raven3 might also be an option if the airflow is too funky? Thoughts, criticisms or comments questioning my sanity are welcome. Pics of rough model and gratuitous dry assembly shot below:

[SpaceManMat]

Convert the piston into an av bay by adding a bottom and all thread for strength. If the piston is not the removable type then you will need to lengthen it so you can access the bottom of the av bay for prepping. Not sure how much room you have. Might need to use a raven as they are very small. The bottom can also be recessed if you need some room under the av bay. You will need to figure out how to vent the av bay also. Possibly vent the top then add vents below the NC.

[RainierWolfcastle]

Convert the piston into an av bay by adding a bottom and all thread for strength. If the piston is not the removable type then you will need to lengthen it so you can access the bottom of the av bay for prepping. Not sure how much room you have. Might need to use a raven as they are very small. The bottom can also be recessed if you need some room under the av bay. You will need to figure out how to vent the av bay also. Possibly vent the top then add vents below the NC.

And along comes option 4, I like it! This is why I ask before building, that's a seriously awesome idea. If I make it with eyes and quick links both sides it should be easy to remove to prep and can be used in later 4" PML rockets. Can keep the motor charge as well as a back up.

As long as the recovery gear isn't too tightly packed I would think that vent holes on top of the piston and under the nose cone should work fine?