Harness for overweight people

I am a beginner and have made a few short climbs. I currently have a rock climbing harness. My problem is that I am top heavy and tend to lean back when sitting in my harness. I have used webbing to make a chest harness but it is extremely uncomfortable.
I purchased a Black Diamond Vario Chest Harness. It is more comfortable put does not keep me up right enough. I know a tree climbing harness would be much more comfortable than my rock climbing harness but would it make difference on my leaning back problem? It appears that some of the tree climbing harnesses have more support for the butt and I think this might help but I'm not sure. I need to solve my physical discomfort problem before I make more advanced climbs. Any help or comments would greatly be appreciated.
Thanks.

A New Tribe harness will be way more comfortable than a rock harness. You'll still lean back with extra upper body weight but if it's combined with a chest harness you'll be getting a better overall tree climbing system.
-AJ

Thanks AJ for the response. I plan on buying a New Tribe Harness as soon as the funds become available.

http://www.treestuff.com/store/catalog.asp?item=2312

I find top heavy climbers that have a high center of gravity and thus tend to need to lean back away to give room for their arms to pull need a chest harness. I recommend the PETZL TOP CHEST HARNESS is super adjustable.

Petzl Navaho Bod would be a good choice.

Hello friends. My name is Eduardo Hildt. I'm from Argentina.
My father has the same problem, and Petzl Avao Bod Croll Harness has not been the solution. It is more comfortable than a rock climbing harness, but does not solve the problem of the back to lean backwards. If the top (front) anchor is connecting to the rope with a carabiner, position is recovered but this is very uncomfortable.
We continue to seek a solution, to preferably not pass by no eat. haha.

Greetings and sorry for the poor english.
E.H.

eduardohildt wrote: Hello friends. My name is Eduardo Hildt. I'm from Argentina.
My father has the same problem, and Petzl Avao Bod Croll Harness has not been the solution. It is more comfortable than a rock climbing harness, but does not solve the problem of the back to lean backwards. If the top (front) anchor is connecting to the rope with a carabiner, position is recovered but this is very uncomfortable.
We continue to seek a solution, to preferably not pass by no eat. haha.

Greetings and sorry for the poor english.
E.H.

A chest roller could work well for your father.
-AJ

Hello friends.
Moss, thanks for your suggestion. We use single rope technique. Finally found the solution with a top-harness homemade, build sewing slings and adding felt to make it more comfortable. This harness (not a life-saving element) passes under the arms and can be closed with a carabiner that attaches to the rope (like a chest roller), to the top hole of the Croll or to the carabiner of descender gear. Is very stable and confortable.



Greetings.
E.H.