BTS bottle with all calories and water in BTA or Frame bottle with all calories and water in BTA? Race is a 70.3

I've read 1000 things and tested quite a few on my own but can't find anything to help me make my decision on where to put my 2nd bottle for upcoming races.

Last year I was just happy to be back out there and took three bottles not caring about those aero penalties but as things have improved I must be more careful.

My main consideration and why I'm skeptical of all those who say under no circumstance should you have a downtube bottle is bc of the aero penalty to sit up, grab the BTS bottle, drink, return it and then get back down and do that every 15 mins. I've always used the BTS as the extra bottle to replace when one is empty.

So I know there's likely a 5 watt penalty at 25mph with a downtube bottle but I can confidently drink out of it without leaving aero position, however the same cannot be said for the other. Does anyone have any data showing the effects of sitting up on aero and that whole process with a BTS bottle? I've tried grabbing it from aero on training rides but it's impossible and dangerous.

I've seen pros that only have a BTA for Ironman distance so do they get special volunteers that hand them exactly what they need? I have no problem refilling my BTA but I would just like that to be water as this strategy works well for me in training. Usually have 2-3 servings of Infinit in downtube bottle and just water upfront and never have any issues but if it's costing me 5 minutes on my bike split I would reconsider.

Thoughts? Ideas? What do you do?

For those of you who say under no circumstance put a bottle on the down tube...or that it should be the last place to put a bottle, tell me in a real world race why, not wind tunnel data. Seems like most people are doing a down tube bottle, but I can see how it doesn't flow with my frame very well. Care to chime in?

I certainly understand that argument and have given it some thought. With the plan I want to run one bottle with all my calories and use the BTA with only water and refilled at stations as needed. In that case I would have to sit up and drink from the BTS bottle every 15 minutes or about 10 times. That's something I do in my training, but doesn't seem to be the best option for a race and exactly what I'm after trying to gauge the penalties for each, but also to understand what others, who would like to have all their calories on them at the start of the bike handle that situation.