Hi Claudio,
well, SAP support should know the best solution available, at least they are supposed 
of course, if somebody can offer you more than that, it is preferred choice for you.
on the other hand I'm wondering are you going to implement really 'all inclusive solution' for SAP Treasury, meaning all instruments, everything? as well, this upload activity form the Client '000' takes just once, so this is just one time activity and in my mind can be handled rather in short time, like 1 - 2 days max.
Kind regards,
Renatas