I got a bumbo for my niece who has cerebral palsy. She wasn't sitting independently but was able to support her own head. It was great. She loved it because she could sit up and use her arms to play. We used it as a feeding chair as well. It helped strengthen her core muscles as well, because it supports but she isn't strapped in in multiple places.

They come up on e-bay (new and second hand), so if travel is an issue you might be able to get one sent to you.

Older kids with CP use them, so a littlie with chunky thighs will definately fit.