there is open trunk switch in the glove compartment
Glove box
R makes trunk
yes, with custom enclosures.
If you have to remove the rear seats No such thing as rear seats in a Miata. I own a 90 Miata as well and locked my keys in the trunk once - NIGHTMARE! under the trunk there are two small "punch-holes. it's not easy, but if you punch the one on the passenger side out, then someone with slender hands can reach up into the trunk and pull on the release wire that runs from the lock to the latch. (Hint: I had to cut out some carpeting after punching out the hole in the bottom of the trunk - I don't know if there is a better or easier way, but that's what worked for me.)
Remove rear seats
Yes, IMMEDIATELY within 3 seconds after punching in your code, hit the 5 on your pad and your trunk will pop open. also if you immediately hit the 4 the other three doors will unlock.
In general, police can search your trunk without a warrant or probable cause if they have your consent or if they believe there is evidence of a crime in the trunk.
Use you key to unlock and open the trunk.
remove rear seat and insulation
There is a sensor that is damaged, bent, broken or missing for this. Much more rare and mostly on older cars the wiring could be damaged to the sensor.
To open the trunk of a Buick Rendezvous without the remote, locate the trunk release button inside the vehicle, typically found on the driver's side near the door or on the dashboard. You can also manually unlock the trunk using the key if your model has a keyhole on the trunk itself. If those options are unavailable, you can access the trunk through the rear seats by folding them down to reach the trunk latch directly.