Yeah it appears to have been in the thought process... It being on a KP style rifle it get's right into your eyes if you flip it around Rock Forward position...
But your thought on the spyder type mount might be do-able...
He used real thick tubing on the Top tube... easy to thread... but to get it to angle upward for DF, that might be challenging...
EDIT: yeah if he made nice brass DF bolt-on part.... that would work.... MATT !!!!! we got work for you !!!!