I reckon a 20ah LifePo would get you where you want to go... but it is a risk as there don't seem to be any dealers for complete batts with BMS and charger in the UK (apart from the weedy 10ah ones, and they don't count.)
Whoa, careful there I might take offence. badnewswade, I think you misunderstand exactly what a 10Ah cell is capable of.
A 36V 20Ah module (12 cells in series, two parallel strings) including BMS, weighs 12.5kg and is 364mm Long X 182mm Wide X 161.5mm high. 2 hour chargers too.
Continuous discharge output is 240A, 20 second pulse is 280A and 1 second peak is 400A. UK company backed 3 year, 3,000 cycle warranty and 9am to 5pm Monday to Friday, telephone technical support.
"commoner" NO, unlikely unless they are unlicensed.
"cheaper" YES, but this is very new technology and it may be another year or two until the licensed LiFePO4 becomes attractive to the general public. Obviously, people will still be attracted to the cheap prices of inferior unlicensed LiFePO4 cells, but these sources will either dry up over the next 12 months, or become licensed and therefore more expensive, as Phostech stretch their legal muscles.