What TR Workout to compliment My Outside Riding

I use TR doing the winter months and once May arrives I start riding outside. This year I entered a road ride that is 65km. It is not a race but I would like to finish with those at the early part of the time. Prior years the early riders are in the 2 hour timeframe. My goal is to get in under the 2 hour 15 minutes time. Currently I can maintain that pace for 40-50k or so.

Currently I am riding outside in the 2.5-3 hour range on Sundays. Likely to get a bit longer as weather improves. Tuesdays I ride a hard 40-50k, say roughly 1.5 hours. My question is what to ride on Thursday and Friday. I dont know that it makes sense to try and fit in say a Sustained Power Build(some of the rides-cant handle all of them) to what I am doing or should I just add VO2/Threshold workouts to my Thursday and then what do I do on Friday. I am in my late 50s and do have some chronic health issues to deal with so recovery is critical. I am also prone to trying to do too much too fast so thought best to get some input.

Any help on what to do would be appreciated.

What TR plans did you do over the winter?