If light pollution is the problem, then any camera will suffer from the problem. A dark sky visit is the best solution, but depending on the type of street lights you suffer from, a light pollution filter may help.
The advantage of your mono camera is that you can use narrowband filters to capture only the emission lines you’re interested in (and therefore don’t need the light pollution filter).
Whether you use a lens or a telescope is up to you....they are just different focal lengths. The best focal lengths really depend on what targets you want to image, but ultimately there is something up there for pretty much every focal length
