There's nothing illegal about your intentions but I think you should discuss your plans with the guide PRIOR to the trip. I'm sure it happens all the time on public waters and there is nothing a guide can do about it except maybe go on social media and express his displeasure with you. I have several friends and clients who are guides and they face this scenario all the time.
If I was in your situation, I would talk to the guide prior to the trip and let him know I had my boat and would be fishing for a few more days. I would use the trip to learn techniques and patterns that were working and apply those to other areas of the lake besides those I fished with the guide on.
I will say this, I've never guided fishermen but I outfit and guide waterfowl hunters each winter. I don't guide on public ground, always on private ground that I have worked hard to gain access to, either thru good relations or paying a daily trespass fee. I catch one of my clients going back to property we have hunted and trying to gain access to said property by dropping my name, we will have a major problem and that person will never hunt with me again.