Tough requirement. High demand, limited options and can't plan far enough in advance. This makes exchanging very difficult to impossible,, esp for the good stuff. The other way to approach this type of issue is last minute (like under 45 days) buy I'm guessing that doesn't fit your needs either.
While all timeshares I know of use the exchange company as a marketing tool, there is no bait and switch. The paperwork clearly states that the exchange company, or even having one as an option, is not guaranteed. IMO
DVC uses it honestly, however, the guides are generally not that knowledgeable about exchanges so I believe they overstate the options and availability out of ignorance rather than intent. IMO II and RCI are pretty equivalent overall when it comes to actual exchanges but you need to investigates the resorts a little more with RCI and you need to plan ahead better since many of the RCI resorts are truly in play 2 years out where with II it was a potential issue but not that common. The difference for II really is simply Marriott and it looks good but is rarely available.
There are 2 groups of exchange options. Those that are NOT RCI points (weeks) may be in play up to 2 years out but it varies with the system, for example, Hilton tends to deposit around 6 months out and Wyndham just under a year in bulk. RCI points resorts tend to not be available until 10 months out. Thus I'd say IF you are looking at RCI points resorts, you're not especially late until 10 months out. The other mistake that I think many DVC members make in exchanges is trying to schedule less than a full week. Even when looking at points resorts, many of them either do not allow exchanges of less than a week or do so only later in the game. They also tend to charge an extra housekeeping fee which can be reasonable or not, often not.
Still, no reason not to try as long as you understand the game and have a back up plan.