Transporting Catfish

I have a pond behind my house with a few catfish. I have a friend with a
well stocked pond and am in the process of taking some fish from his pond
and putting them in mine. I usually transport 20-25 at a time at a
distance of 35 miles (takes about 45 minutes). The are transported in the
back of my SUV. These fish are caught with a rod and reel, I only keep the
ones hooked in the mouth.

The fish are 1, 2 and 3 pound fish. Currently I have a small 20-60 gallon
Aquarium Air Pump with dual hoses that I run on a battery pack into a 45
gallon plastic storage container with a lid. I put some ice, but not very
much to cool the water.

Today, I moved about 20 fish, but three died in transit (not a real
problem, I will eat them tonight!). I am worried about the others I put in
the water though. They swam off pretty good, but I want to give them the
best chance to survive.

Can anyone give me hints on the best way to keep these fish alive? Should
I use more ice to cool the water more? Do I need a bigger container?
Anyone have any suggestions for a bigger container? Do I need more airflow
than the small aerator I have?

Any hints would be appreciated.

Thanks!