I combed through a few related threads, but I’m still a little stuck on how to approach the first half of my 2023 training plan.
I have a planned A Event (ride, not race) on 6/17 (140 mi road w/ 9000’ of climbing) and I am also debating a marathon in early May, which would give me about 6 weeks between events. I considered low volume full distance tri plan (dropping swims) with the marathon as the B event. My concern is that the full distance won’t have me fully prepared for the run if I anchor it to the 6/17 A event. Another approach could be to use the TR plan to focus exclusively on building for the A event and planning out my run separately.
Any advice is most appreciated. Cheers all!
TR Plan Builder requires A events be at least 8 weeks apart. 
Perhaps set the tri plan with an A event of 6/17.
Plan out your runs separately for the marathon for the specific run sessions aiming at early May, but use TR as a guide for how to fit them into your week around your bike sessions (I hope that makes sense).
Once you have completed the marathon, delete the plan, schedule a recovery week, then set up a new plan targetting 6/17 as your A event (presumably a Fondo?) Which will likely be Century speciality squeezed into 6 weeks.
I have a similar first half of 2023: marathon on 05/20 and 100 mile ride on 06/17 (8k feet of climbs). I debated for a while about doing a full ironman block, but decided to set the ride as an A event and plan my marathon training block outside TR, then uploading the runs. Hoping TR adjusts accordingly.
My reasoning: I prefer a higher-volume, lower intensity approach to the run. At least my body responds better to that.
In TR, went with a LV build. Will add low intensity Z2 rides on top.
Good luck, and do please tell what you end up with.
Are you running or racing a marathon?
Are you sure this is a good idea? A marathon takes a lot out of you and a long time to recover from. Beyond the muscle and training impact lots can happen. Even if you are just doing it as a run it could be a week or two of rest before you start training again.