I would NOT discourage you from touring the Rhine Gorge in the off-season. If you are like the Rothenburg-fans who rave about R'burg's quiet streets in the late evenings and early mornings, when the day-tripping tourists are absent, you will probably like Rüdesheim in November, a time of year when this handsome town is pretty much tour-horde free at any time of the day.
You should probably make some seasonal sightseeing adjustments, however. In November, average daytime temps are in the mid-to-high 40's. BRISK, and not comfy if you were sitting idly on the open deck of a cruise boat (which is a remote possibility but not advisable!) But the mid-40's are just right if you are walking around old-world towns well attired. And in recent years the late fall months have been seeing fewer cold weather days as the climate undergoes change. Some of my best walks here (and elsewhere in Germany) have been from October - December.
Average rainfall in November is less than 2 inches - not much at all compared with summer rainfall - but what matters is the weather during YOUR visit, which is simply not foreseeable. Walking up to Marksburg takes about 25 minutes, but you might not be a happy hiker if it's wet/slippery, so as your visit approaches, the thing to do is to keep your day-to-day sightseeing from Rüdesheim flexible; you should be able to learn, when you wake up on the 11th in R'heim (your latest plan,) what the weather will be like over the next few days. Also, because hiking the famous Rheinsteig trail is one of the main reasons for staying in Rüdesheim and the other east-bank towns, the R'heim tourist office, which will be open that Monday morning, should be able to inform you on trail conditions:
https://ruedesheim.de/en/contact-tourist-info/
Braubach (Marksburg) also has a TI office you can contact or visit for advice of all kinds; page is in German but English is spoken:
https://braubach.welterbe-mittelrheintal.de/stadtpolitik/ihre-ansprechpartner
That said... there's no reason you have to walk up to Marksburg, no matter what the weather is like. The TI office can surely give you advice on taxi services. Here's a contact page for a Braubach-based taxi service I am aware of:
http://funktaxi-braubach.de/kontaktzuuns/index.html
There probably will NOT be an English-language tour of Braubach. But honestly, a tour in incomprehensible English is probably no worse than tour in incomprehensible German. I do not know the Marksburg guides - but I can say that poor pronunciation, intonation, etc. on the part of English-speaking German tour conductors has been a serious problem on about half my tour experiences. The handout can be huge asset no matter which tour you get. Many thousands of French, Dutch, Asian and other tourists with no German use it too :
https://www.marksburg.de/assets/uploads/Marksburg__Guided_Tour_in_Englisch_2021_.pdf
Braubach's old town is a delight:
https://fotos.schloemp.eu/wp-content/gallery/braubach/002Braubach-Bauernschaenke-Eck-Fritz.JPG
https://fotos.schloemp.eu/wp-content/gallery/braubach/020bBraubach-Marktplatz.JPG
I like the traditional German food at Braubach's zum Goldenen Schlüssel (closed Wed & Thu.) It serves locals as well as tourists and does not close down when tourism slows. Open mid-day hours for lunch and evening hours :
https://image.jimcdn.com/app/cms/image/transf/dimension=1070x10000:format=jpg/path/sc484ea64eed53c8f/image/i82e0948970fa8d90/version/1550765364/image.jpg
It is true that some small towns close down almost entirely. St Goar comes to mind... The St. Goar ferry is handy for train travelers crossing the river, but St. Goar would not be on my list for a November visit, only for crossing perhaps and then hopping on a west-bank train to somewhere else. Bacharach is not on your list, but I would definitely recommend a stopover for at least 1 hour just to check out all the handsome half-timbered buildings.