I did 600 miles in 6.5 days in June across the length and breadth of Scotland - including 30,000 ft of climbing. All on a 50lbish road bike & panniers/kit
I am 40 something and weigh 15+ stone. Only been cycling a couple of years, but its all about conditioning. I have mates who are ultra fit runners, but its a different set of muscles - hill walking is the nearest to it if you want to cross train as well as cycling. The runners struggle to do much more than 20miles on a bike without a lot of practice.
Whilst I didnt get as much training in as I wanted I was doing up to 3x40mile commutes a week (20miles each way) two spin classes (often as well as the commute) plus a good 30-60mile ride at weekends. I didn't manage this all of the weeks weeks but tried to do it as much as possible for the last couple of months. Managed 1 x 100mile sportive about a month before the trip.
On the ride it was tough, but averaging about 13-14mph throughout the day meant it was always achieveable - avge would have been higher if it werent for the hills which were a struggle with my weight & kit - but was never defeated.
By the last day my (and one of the other two guys) bodies were craving for a rest - I couldn't get my heart rate up and my body was restricting me doing anything too much.
In summary though, with your age, plenty of training, a bit less kit (I took way too much) and less hills it should be doable without too much trouble - be prepared to take a rest if necessary.
As an aside I got my eating very wrong - managed to convince myself I needed to eat all day (sweets, cakes, full-fat coke, tea & sugar, cooked breakfasts, lunches, dinners etc) and as a result despite burning 4-5k calories a day managed to put on 9lb!!!!
Good luck - for me it was a brilliant experience and I wouldn't hesitate in doing it all again.
I am 40 something and weigh 15+ stone. Only been cycling a couple of years, but its all about conditioning. I have mates who are ultra fit runners, but its a different set of muscles - hill walking is the nearest to it if you want to cross train as well as cycling. The runners struggle to do much more than 20miles on a bike without a lot of practice.
Whilst I didnt get as much training in as I wanted I was doing up to 3x40mile commutes a week (20miles each way) two spin classes (often as well as the commute) plus a good 30-60mile ride at weekends. I didn't manage this all of the weeks weeks but tried to do it as much as possible for the last couple of months. Managed 1 x 100mile sportive about a month before the trip.
On the ride it was tough, but averaging about 13-14mph throughout the day meant it was always achieveable - avge would have been higher if it werent for the hills which were a struggle with my weight & kit - but was never defeated.
By the last day my (and one of the other two guys) bodies were craving for a rest - I couldn't get my heart rate up and my body was restricting me doing anything too much.
In summary though, with your age, plenty of training, a bit less kit (I took way too much) and less hills it should be doable without too much trouble - be prepared to take a rest if necessary.
As an aside I got my eating very wrong - managed to convince myself I needed to eat all day (sweets, cakes, full-fat coke, tea & sugar, cooked breakfasts, lunches, dinners etc) and as a result despite burning 4-5k calories a day managed to put on 9lb!!!!
Good luck - for me it was a brilliant experience and I wouldn't hesitate in doing it all again.