SV hard luggage question

If you have a top box fitted that goes where the pillion seat would, rather than behind where a pillion would sit (specifically, the official suzuki one), can you still fit throwover soft panniers? I know the Suzuki one has a plate that goes where the pillion seat was which the top box connects into, I was wondering if the straps could be fed through there or if that'd foul the top box being connected in.

on the same subject where can you get the plates?

[Luckypants]

I know BluePete made his own topbox to replace the pillion seat from a second hand seat base and givi top box. Perhaps he can give details (or maybe already a thread on here).

Using an old pillion seat as the base would allow the soft luggage straps to be routed under the top box/base in a similar fashion to how we fitted SpeedyClaire's panniers under her tailpack (which fastened to the pillion seat).