A few clippings from Melody Maker (second one mentions a Bonham solo) (July 6th, 13th and 20th, 1968).
Also, re the Tim Rose appearance on Top Gear (July 1st, 1968), although Dougie Wright is listed as the drummer (source), that sure does sound like it could be Bonzo. Maybe it's just wishful thinking.
Have a listen here.
Track 1 - Roanoke: drumming with his hands (1:55)
Track 2 - Foggy Mountain Breakdown On Rye With Mustard: multiple drum rolls (e.g. 4:34 & 5:00-5:20)
Track 3 - I Guess It's Over: drum rolls throughout [triplets?] (e.g. 6:40, 7:00, 8:16, 8:20 ...)
Track 4 - Long Haired Boy: multiple rolls throughout but harder to make out (e.g. 11:00)