I'm in a similar situation but I'm 7 months out and just started backpacking again. If youre only a month or so out, id talk to your docs first.
I realized this weekend after doing a 2 day, 15 mile hike, that I should get a bladder so I can take small sips. I've been going long distances without drinking but then can't stop myself from chugging the Water, which I then regret. I'm planning to get a 3L bladder for my next hike.
food wise, I'm not sure what to do yet. I think I'm going to budget to stop every 2 hours for a snack. However, I found I really have to wait 20-30 mins after eating or I'll get nauseous on the ascents. I've been starting the day with a Protein shake pre-hike, then snacking on cheese, summer sausage, kind bars, high protein granola, etc. throughout the hike.
I give myself a lot of leeway when hiking, considering how many calories I'm burning throughout the day. That's probably not the best tactic though.
7 months out and I can do a lot more than I could pre-surgery but I'm still weak and slow, which I attribute to not being able to get the calories and water in.