Solstice Sprint 2025

I know it’s a road event 😧 but thought I could draw on some people’s experience here.  1000km starting in Warwick heading into Wales with ~10,000m climbing.  Hoping to do it in 3-4 days so expecting 2-3 nights Bivvy bagging.  

Bike - Cannondale Supersix evo

Kit list:

On bike:

• Front light
• Rear light
• Pump
• 2 x 1 litre bottles 
• Tubeless repair kit

Top tube bag:

• Tubes x 2
• Tyre boot kit
• Multitool
• Lube
• Tyre levers
• Zip ties
• Fast straps
• Carbon grip paste?

Under top tube bag:

• Power bank
• USB C cable
• USB cable
• Fast charger
• Foil blanket
• Chamois cream
• Sun cream
• Tooth paste and brush
• Painkillers
• Contact lenses
• Buff
• Bivvy pegs
• Bivvy poles
• Electrolytes

Saddle bag:

• Hooped Bivvy
• Sleeping mat
• Down jacket
• Waterproof
• Gilet
• Merino top
• Light weight shorts
• Spare socks

Aero bar bag:

• Down sleeping bag 

Riding kit:

• Hi vis
• Bib shorts
• Jersey
• Cap
• Socks
• Gels
• Bars
• Helmet
• Sunglasses

Assuming it’s normal ish June weather should I swap out the 3 season down sleeping bag (800g) and try to sleep in merino leggings, down jacket, silk sleeping bag liner and the foil blanket (compulsory item)?