hmmm... 40 Vpeak seems to be in the range of 200 W @ 4 Ohms or 100 W @ 8 Ohms HIFI amplifiers. maybe you can re-purpose one of those, remove the slew-rate limiter (if even necessary) and then feed it with a signal generator? the "better ones" in the good ole days of hifi were sometimes marketed with BW well beyond 100 kHz. could be juuust enough.
don't know about the peak current handling capabilities, though.