I hope you don't mind me suggesting it, but perhaps there are other options? Monty has OCD as part of his ED, but please don't let this worry you as it might be nothing.
If you are going to go for A, I would combine it with an anti inflammatory. Six weeks lead walking will help to reduce inflammation, but even if Kipper doesn't appear to be in pain they are good at hiding it, and a limp does mean he Has discomfort even though it might be intermittent. Combined with weight loss, you could see how it goes for the next month or so.
If it doesn't work, or you want further investigation, can I suggest you get a referral to a ortho specialist and have a CT scan? This is my logic.... if you go with A and it doesn't disappear, you will go back for X-rays. Anything that shows up, unless your regular vet is also a referral centre, they are going to send you off to a specialist anyway. The two ortho surgeons I've seen weren't even interested in the x rays I showed them, as far as they were concerned only a CT scan would give them the best chance of a definite diagnosis. Please don't worry about the GA, they are incredibly safe- and by going straight for CT you would limit it to one GA anyway. As for whether you have anything done while he is under, I'm not sure, that's probably a few steps away anyway.
Also, the specialist will spend lots of time manipulating joints and testing for flexibility, movement and pain, and will feel other joints, you could get shoulders and wrists checked out too.
Of course, if his X-rays come back clear it will give you some peace of mind..... but if he's still limping you will probably end up being referred to a specialist centre anyway, and again, they are likely to recommend CT.
Another thing to do alongside this, is see if you can find a vet who specialises in pain management, they can do physio, laser treatment, acupuncture, - if you could find one with a gait analysis mat this would also be useful to you as firmly identifies which limbs, and to what extent, are causing the problem.
I don't know if it helps, but I had quite a long thread on the old forum of our process of getting diagnoses. However, I don't want you to get stressed about long term problems when there simply might not be any.
On the weight thing, nothing to add, other than the first thing we did was switch to a light kibble, with fewer calories in but gave enough satiety, and then of course you can look at adding in veggies too, to increase bulk but not calories.
Ps, this is only my own experience, not based on anything more. We have had subsequent X-rays to check progression of the ED and HD. Monty luckily bounces right back from GAs, he's had at least six now.