Keep your vet (and farrier too?) involved if you have any reservations about how it might be healing, or if you think any infection is stuck in there. Other than that, give it time. Has it even been 8 weeks yet? As I understood it, your horse bruised his sole corium and it abscessed, then got infected. Is that correct? Well, I'm sure you've seen a half-section of a hoof? Take a look at what your horse is still needs to heal and regrow, and understand that underlying corium and tissue could have been damaged. The sole that grows will be thin. It has to keep growing, compact under the horses weight, and grow more. You can help that along with rehab, but don't be in a hurry for that growth.
Keep walking him as much as possible. Make sure your padding/covering (inside of the hoof boot) provides some gentle pressure and release (stimulation) to the sole as well.
The 8 week mark seems an appropriate time to mention this: You might eventually want to stop stuffing the hole with treatment packing, or just don't do it every day. No matter how deep it goes, your packing might be interrupting/blocking/warping any new growth and healing measures in the hoof. Something internal might want to adjust or tissues might want to reconnect, but the packing is blocking that. You can keep treating against infection and covering the site, while leaving the hole open. Do keep that area well padded if you suspect the sole is thin. If you can find foam between 1" and 1.5" thick that squishes down to about 1/4", you can cut it to fit inside of your hoof boot. Similar to Easyboot Cloud insoles, I'd think.
Can you show us a new photo, too? It'd be nice to see how things have progressed, even if it doesn't look like much.
No diet, no hoof. No hoof, no horse. No horse is not an option!