New to Vespa PX - Double Saddle Fitting

Hi, newbie with a technical question. Have a 2016 Vespa PX 125, love the look of the classic Vespas and wanted to fit a single saddle seat and a back cushion to my modern PX but also wanted to add a backrest at some point.

Been informed that due to needing a mounting plate to fit the cushion, I would not be bale to fit a backrest.

I have seen here on S.I.P that there are options for front and rear single saddles. Therefore my question to anyone who can help would be -

Would it be possible to fit 2 single saddle seats to a 2016 PX 125 ( S.I.P item numbers 24105610 & 24104670) and still fit a backrest ?

Any help appreciated.

Many thanks