I've done it. I've been trained to do it. But I don't have the equipment to purge and I just collimate the old school way looking at the stars and making adjustments til everything lines up. It's not hard to put together, but it is easy to break stuff if you don't know what you're doing. I usually just argon purge mine with my welding tank. If you have manual gain, then the complexity can get worse but it really depends on your tubes and the housing you choose.
Yeah you'll need another set of lenses and a tube. You'll probably want to make sure you buy the same brand lenses that you have. Like don't combine a Carson with an AGM or aliexpress.