I just did an 800km ride and found myself wishing I had central pegs for posture relief. I wasn't in pain but the option of changing riding position would help a lot.
So I've decided to make a set using Dwight's design shown
here. I'll get them laser cut so if there's any Aussie members who want a set of centre peg brackets just let me know. I haven't priced them yet but it won't be expensive. I will probably make them out of slightly thinner plate. Dwight used 5/8" thick which seems unnecessarily thick - so maybe 3/8" will suffice.
You will still need to...
... source your own pegs and foot peg extensions and bolts.
... paint or chrome the brackets.
Personally I will just paint mine black.