I acquired a Japanese saw some weeks ago with this activity in mind. I had always wanted one, having seen a lot of builders use them. Mine came with two blades - rip and cross cut. This is it with the cross cut blade fitted, ready to cut the tabs in the bulkhead.
I removed the port side first, as here.
The saw cuts on the pull stroke, which takes a few minutes to get used to but is extremely effective. It is also incredibly sharp, as I discovered to my cost within seconds of cutting the first tab when the saw jumped and hit my carelessly placed hand and drew blood ...
And here is the starboard side removed.
Finally I tidied up the tabs and rough epoxy, sanding all smooth, as here.
And that was bulkhead 7 all done!
I was very impressed with the Japanese saw. I used it to cut halving joints on another small project, and it produces clean, smooth, accurate cuts which need minimal paring with a chisel to finish the joint. I won't be using my tenon saw any more!