Thought I would add a few suggestions to address the questions above.
The Half Monty is considered a sub maximal effort as a test. If you are referring to the HM being part of your plan I would do the test as scheduled as it will be used to adjust your power numbers and targets. If you are thinking of completing the HM as a stand alone test you will be okay to do that as long as it is 5 days after doing the 4DP test.
If you split up your long endurance rides into 2 rides you will lose the endurance/fatigue and nutritional demand components of the ride. That said, to try to fit in workouts or rush them and not have proper training readiness will not give you the desired results either. The key is to be honest with your goals and time that you have available to train. Another suggestion would ,be if you can, to do a SUF workout such as The Cure and then add an hour of endurance afterwards. The SUF workout will give you the training stimulus you need and then to add the endurance afterwards will give your body the endurance stimulus. You can pick the SUF workouts that work on your particular weaknesses and then add the endurance. Although this may not be the “Hour” total the plan has listed you will still get benefit. The additional endurance training time will also give you time to practice your nutrition strategies.
When combining plans always be sure to take a recovery week in between the plans. Your recovery/adaptation time is just as important as your actual training stimulus time.