Ecobubs pockets are good for chubby thighs.
I wouldn't say tutto woul be good my friend and my sister have quite long chubby boys and they both can't use them even though they fitted before. One isn't even 6 months yet and they dont' do up anymore.
Prefolds are great but I can imagine the bulkyness.
You could try just a standard Itti bitti. A medium SIO would work. I think that large itti bitti seem to fit bigger children better than tutto would. LIke my 3.5 year old can still fit a large but not a tutto. He's average in size though.
Hope this helps.
Edited to add: Duh you were looking at OSFA. Any decent OSFA pocket would work, but they are bulky. Bubblebutt nappies. LOL I know lots of people swear by pop ins. They are very trim, but I can't mange to get mine not to leak.
Maybe look at nappy days.co.nz they have a few OSFA and they are brilliant.
Edited by BessieBear