For the last 45 years I've typically requested VFR on top on an IFR clearance when I'd be in and out of clouds.
VFR On Top isn't common and it might simply be that the controller didn't understand it.
If you are on an IFR flight plan and are above the clouds, you can request and receive a "VFR on top" clearance.
Meanwhile, the "VFR on top" IFR clearance is a specific, approved operation.
We spiraled up through a hole in the clouds to establish ourselves VFR on top
in the vicinity of Pauma Valley, about 20 miles to the east of MCAS Camp Pendleton.
Many IFR pilots might look at a severe-clear day and consider obtaining a VFR on top clearance.
While a VFR on top clearance can be useful on many days--when there's a cloud deck with good VFR below it and above it, for instance--today's CAVU isn't necessarily one of them.
VFR on Top is just another altitude assignment while on an IFR flight plan.
I've usually been denied VFR on Top while trying to escape what I thought were onerous restrictions in busy airspace.
In this case, the type of IFR clearance you might want to consider is the climb "to VFR on top
Plan C was to go VFR on top
until it was time for the approach and then fly it so as to minimize my exposure to potential ice.
Note that "to VFR on top
" is not the same thing as "VFR on top
" (where you're still on an IFR flight plan, but at a VFR altitude in visual conditions).