Thank you for the feedback Ryan! Since Ryan comes from a hardcore cycling background, he has a lot of great experience to offer and it sounds like he is recommending practice too!
As Ryan mentions it is always more efficient to remain in aero than to be getting in and out. So come race day, the more you can stay in aero the better. However one of the reasons the trainer is harder for you is because you are not as able to move around. You are truly locked in. So there are some advantages to moving around like minimize cramping, stretch out tight muscles, etc. The more you practice in aero the longer you can stay in aero without issue.
However remember that you need to get off and run a marathon so if you need to take some time out of aero here or there, it really won’t hurt you. In addition I was always trained that you should get out of aero on hills to increase your oxygen consumption, keep HR down, etc. This differs from what Ryan recommended.
In the end, it really does come down to practice. So get outdoors and figure out what works best for you!