Correct on the rear fender and number plate bracket. The rear lamp "fairing" (glassfibre part) is the stock Roadster item for the "beehive" taillamp with the front tip trimmed off just as it passes the rear frame loop; this is to match up with the rear edge of the stock RP seat. This is my rough sketch, modified from an Andover-Norton parts diagram. Not shown is a hole for a screw at the front end of the trimmed fairing; a screw goes through this hole and threads into a counter-bored and threaded larger screw that fixes a "C" clamp over the rear frame loop to secure the mudguard. WIth the seat off, that "C" clamp is naked (covered by the stock front end of the fairing) but it's covered by the rear of the PR seat.
View attachment 111862
The first PRs had black-painted steel rear fenders, as B+B says, from the Fastbacks at the time. The later ones went to stainless. There were also two different front mudguards in glassfibre; the earlier ones were slightly wider at the mounts to the fork sliders and tapered less so that they had a gently rounded front and rear tip, the newer type were narrower at the mounting area and tapered more so that the ends were almost pointed.
A New-York based photographer named Allan Tannebaum was traveling in the UK and Europe photographing motorcycles about August, 1972. He called in at the Andover factory (as well as the Ducati factory on the same trip) and he has some good photos of the production line with some PRs being built - his photos were published in a contemporary magazine but, sorry, I don't have a link - but they show good detail with some PRs with tank on and some with tank off.
About the same time, there were at least two later-spec PRs and an "AMA" spec racer built at Wolverhampton, general Commando production assembly being moved to Wolverhampton at the time. I believe the idea was to produce another batch of PRs at Wolverhampton but that never happened. There was one 850 PR built in the Experimental shop at Wolverhampton in later 1972 with a "John Baker"-built special 850 engine but otherwise like the other later PRs except all the glassfibre parts were produced in red. That one is probably the last factory-built PR and it's the one I'm most familiar with (it's sitting in my workshop now, as it has since 1972).