There aren't any over the counter baffles that would work that I am aware of. Because of the length of the body tube, the baffle needs to be relatively short. Something in the 2.5 to 3.0 inch range if you still want to have ample room for the recovery gear. The baffle I made for this rocket was 2.5 inches in total length.
There are also differing opinions with the distance the baffle needs to sit from the top of the motor. I've heard everything from 3 inches to more than a foot is required. In practice, I have built multiple rockets with the baffles as close as 1 inch from the top of the motor tube and flown them successfully without deployment failure or any type of negative effects on the baffle itself. This Big Red Maxx has 4 flights since being built and all were successful with good strong ejections.
As for the room required. The pic below shows the position of the internal components. If you keep the Baffle compact there is more than enough room easily get the recovery in there without forcing anything. I've even flown with an altimeter on board.
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The baffle for this rocket was made using a 2.5 inch long piece of coupler. I then cut two pieces of 29MM motor tubing for the internal tubes. Each internal tube is 1.5 inches long. I don't have pics of the inside of this baffle but I do have pics of the exact same baffle built for another rocket. The only difference is the other baffle is 4 inches long. Otherwise the materials and build process is the same.
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The internal tubes were glued in place on the inside walls of the coupler. The end of the tubes overlap approx. 1/4 inch so that none of the ejection could jump from one to the next.
The baffle was capped top and bottom with lite ply caps.
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Since I added additional weight to the rear of the rocket using plywood fins, rings and a baffle, I needed to add additional nose weight. TO make this easier I cut the bottom of the cone off and replaced it with a bulkhead. Note that I also recessed the bulkhead giving me additional space inside the tube. This isn't mandatory but it is another way to gain more room if you need it.
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