I find it odd that they didn't make use of Roach. I thought that was going to be part of the point.
Personally, I find it a bit jarring to have him appear out of nowhere. Reminds me of the shop keeper from Mr. Benn (obscure English Children's T.V. show), *but* since he's there, then I would have thought that he would have been ideal for storage.
There are saddle bags, so maybe give the saddle bags a greater capacity, but give them to Roach. Or maybe make them have a special capacity, for weapons/armour/ores/metals etc. It's a bit weird that Geralt is carrying the bags, but maybe it's implied that Roach is carrying them. Since Roach is summonable from almost anywhere, then why not make him a type of permanent extra storage. Maybe not infinite. Maybe upgradable. Saddle bags, with sword/armour harness, for extra capacity. Ore/Metals bags. etc.
Also, seems very odd to be in the same situation from The Witcher 2.