A very good suggestion By Mr.D.I. quite feasible.
The Govt. should give an option of receiving RTI replies on E-mails.
An applicant could make a fresh E-mail I.D. and then shoot the anonymous RTI and then get the scanned copy of reply duly signed and stamped from PIO from official E-mail I.D. whose printout may be considered a valid documentary Evidence.
This can further liquidify the chance of being identified while going and receiving the reply in person to post office any other Govt. Office.
I m not sure ,just fancyful, may be wrong also....