You can do that, however keep in mind that if something goes wrong such as you lose too much strength, muscle, etc, you won't know why if you are not counting calories. However, as long as you know beforehand how many calories you will be consuming each day, you can avoid all that work. The easiest way, if you do not want to count calories on a daily basis, is to make up a diet plan. A plan which you do know the calories, macronutrients, etc. Then stick to that diet plan. If boredom with food is a problem, then make two-five different diet plans with different foods but with relatively the same amount of macros and calories.
If your 5 RM stays about the same, then you most likely have maintained most of your muscle mass. However, keep in mind that you will temporarily lose some strength just from cutting calories back. Usually you regain this strength after a few weeks of lifting once you've gotten calories back at maintenance. The best tools we have to measure whether you've maintained most of your muscle is a combination of strength testing and using calipers to check skinfolds on a regular basis.
Squat - 485 lbs
Bench - 315 lbs
Deadlift - 635 lbs
Total - 1435 lbs