Stop the second attempt at the end of the year, Steve to rest up and then train for speed through the rest of Winter at least. Once the numbers look good enough (relaxed flatland average around 19-20 mph), start a third attempt, probably in Spring. Use the down time to check out possible food and equipment changes and arrange the new support set up.
Alicia is the biggest advantage Kurt has had. She has kept him focused, studied the weather, sorted accommodation and so on. Every time Kurt has weakened mentally, she has adjusted the situation, arranged riding companions and brought him back on track. She has been (mostly) able to keep him riding, despite multiple efforts to destroy bikes.
Given that a fit Steve is almost as fast as Kurt, Steve needs to ride a little more time each day than Kurt does. Assume 7 hours sleep a night (can't afford any sleep deprivation) plus another 2 hours to shower, shit, dress and a sit down meal or 2. Allow up to another hour for traffic lights, pee stops, adding or stripping off clothes on the road, medical, etc. that leaves 14 hours each day that Steve can actually ride. If Steve had somebody to hand him up water and food without stopping or to hand him a rain jacket, warm clothing or a replacement bike, along with routes with minimal traffic lights/ stop signs and good use of tailwinds, that would allow him to achieve up to 250 miles in a day without losing sleep that kills distance the following day. RAAM riders brush their teeth while riding, not while they're stopped. Everything should be aimed at minimising the number of minutes that Steve is riding at less than 15 mph and ideally minimising time spent below 18 mph.
He should be eating solid food on the bike more and using things like Winter & Summer Training Fuels (developed for Hoppo's first RAAM) or other such drinks that suit his stomach to reduce the time spent stationary. Nuun is good hydration but not enough by itself.
Plugging into a headwind all day is counterproductive. No more than an hour at a time into the wind. If Steve wants to ride laps around a fixed base (Milton Keynes?), pay somebody to look after the home base - clean, prepare and hand up food and bottles, wash and periodically disinfect clothing. Home help on Steve's team (Lesley) has been wonderful but she has plenty of other demands on her time and that can't be ideal for Lesley or Steve. The bike maintenance aspect has mostly worked too. Currently Steve spends a lot of time stopped in Milton Keynes. How much of that is doing stuff that somebody else can do while he is on the bike?
Otherwise you are looking at a motorhome approach like Kurt or at least a motorised approach, to chase the combination of tailwinds and fast flat roads. If so, you want 1 or 2 people available every couple of hours whenever Steve is awake. That is a lot to ask of volunteers. Driving Steve upwind should occur EVERY time there is a consistent wind but daylight hours shouldn't be wasted in a vehicle. That pretty much means driving across the country in the evening while Steve eats/ sleeps, otherwise Steve runs out of England before the next day's ride finishes.
In contrast to Alicia and Kurt, Steve's team has discouraged anybody from riding with him. Steve is hard as nails mentally but riding with others not only helps instantaneous speed but maintains the rider's focus and enthusiasm. It also makes it easier to find out about little niggles (e,g, medical or equipment) and take steps to fix them early. That works best with traffic-free/ traffic-light laps of a flat circuit with a fast surface.
Steve's wheels, tyres and aero position are already pretty good. There aren't many gains to be made there. A lighter bike would help in the hills but the idea is avoid them completely anyway. There isn't much aero advantage from a different bike frame at less than 20 mph.
I think Steve carries too much stuff on the bike all the time, mostly because he doesn't count on anybody's support all day. If Steve has access to everything he could possibly need every 2 hours or less (just call), he doesn't need to carry it with him. That is a significant difference from his current approach.
Steve needs to do interviews only while he is riding, either by phone or with somebody on a bicycle or motorcycle beside him.
The team needs to be small but able to replace people during the attempt. A year is a long time for anybody to commit to supporting Steve and circumstances change. At least one person on the team should talk with Steve each day and should look for what he isn't saying, not just what he does say.
Steve's performance needs to be closely monitored and appropriate adjustments made without delay, otherwise deficits grow quickly. There should be daily or at least weekly updates on what is happening.
Just some thoughts late at night. There are a lot of possibilities to optimise this rough outline but basically it is an extension of how HK and I supported Steve through 3 x 24hr TTs, modified by HK's experience of fitting high annual mileage targets around life and work, which leads to a 'minimise wasted time' approach.