First no napping on the couch - use a mat with a waterproof cover. Also consider getting a vinyl table cloth and putting it on the couch if a mat isn't an option. Serve lunch earlier so there is 30-45 minutes between drinking at lunch and bedtime then there is time for a full pee to be done in the toilet before nap. If he is soaking a pullup then switch to huggies goodnights for nap as they are intended to hold overnight pees.