I agree with DaveP that the Racktime rack will be a much better product than your current rack. (Racktime are a sister company of Tubus, who make the best bike racks full stop, i.e. the ones people choose for heavily loaded cycle camping and round the world tours. Tubus racks are steel, and they set up Racktime to make a similar range of racks in aluminium with features like the SnapIt). Once installed I don't doubt it will be a very nice set-up to use with the Vaude bag.
However, I am somewhat sceptical about getting a local bike shop to fit the rack. I suspect the bill would be higher than I would be happy to pay, because it will probably be a fiddly task and potentially very time consuming, especially so if the shop lacks the right tools, spares and familiarity with that type of task and the components
. A shop that specialised in e-bikes and was familiar with making modifications to the rear lights and their connections and
which stocked Tubus racks would possibly do the job well and quickly. I suspect too many average local bike shops would be likely to take too long (=excessive labour charge), and would bodge it, because they would not have the necessary components and familiarity with the task.
I suspect that to fit the rack it will be necessary to purchase:
1. The Tubus Mudguard Holder
, unless you are lucky and the existing bracket joining the mudguard to the rack can not only be re-used but will be in the correct position for the Racktime rack (unlikely).
2. Extra long Tubus Roundstays
. I am fairly sure Racktime use the Tubus Roundstays. A longer Roundstay than is typically supplied with the rack will make it much easier to put one or two bends in the Roundstay to route it around the lock.
3. Alternatively or possibly in addition to the longer Roundstays, a seatclamp with integral rack mounting points. This would be my preferred option, because they are easy to fit and work well (no noticeable lack of rigidity with a Tubus rack for example). However, you would need to get the correct size, and I think the two sizes in the link above to the one sold by Condor would be the wrong size. SJS sell four sizes here
. Those sizes correspond to the external diameter of the seat tube, and you would need to check the external diameter of your seat tube where the curent clamp attaches. Unfortunately the 29.8mm is out of stock at SJS and the UK distributor
, and I suspect that might be the size you need. However, SJS do have 30.0mm in stock in another brand
, and that would probably also fit. The Roundstays supplied with the Racktime rack may be too short to reach the clamp, so you might still find that you need to buy longer ones.
Another issue will also be whether the existing cable to the rear light (assuming it is the unit on the rack, and that what is on the mudguard is only a reflector) is long enough to allow the light be fitted to the Racktime rack. If it's too short, you will either need to splice and extend the cable, or fit a stand alone battery light in its place.
Before doing anything else, I suggest you wait until you receive the new rack. When you get it, offer it up to the bike and see how it is likely to fit compared with the existing rack, e.g. are the supplied Roundstays long enough and how close is the plate on the rack for the rear light to the position where the rear light is on your existing rack*.
* Hold the new rack alongside the existing rack, with the mounting holes at the bottom of the rack aligned with the bolts securing the existing rack. Make sure the top of the rack is level. Compare the relative positions of the existing rack's light and the corresponding plate on the new rack.