First off, it is difficult to get customers to pay for maintenance coats when the deck is still looking good to them. Even so, you will be creating a multi layer coating situation that will be extremely difficult to deal with down the road.
Stong sodium hydroxide based strippers are about the only way to remove the coating. Frequently, when using strong strippers and higher than prefered water pressure, the wood will develop the nasty fuzzies that are not very becoming.
In my opinion, the most difficult task of stripping decks, are the spindles of the railing. Belt sanders do not work very well on spindles, and the chemicals don't cling very well on vertical surfaces. I suppose you could sand them with a palm sander, or a dremel.
So what you are proposing, is using one of the most expensive deck stains available, then charging them more money to maintain it every year. I don't see how one can continue to recoat over and over without problems.
Then, when the time comes for a complete strip, you will have to charge them another exorbitant price for removal.
I don't think they will remain your faithful customers for long.
Why not look at a product such as Ready Seal, that is much less expensive, and far easier to maintain? If your sales technique is polished, it won't matter what brand of product you use, so long as you present it in a thoughtful, professional manner.
I'm sure others could add their two cents here as well.