If the claim has not been settled yet, here are some suggestions:
1) You may be able to force the adjuster to provide you with a rental unit. The purpose of the insurance is to restore you to the position you were in before the loss. If camping is a part of your lifestyle, they are obligated to assist you in resuming that life you had before the accident. Now, they may not rent you one for 2 months straight, but they may rent you one for a week or for a few days. Better than nothing, huh?
2) If you live in a state that allows diminished value claims, get an estimate from the dealer of the value of your unit before and after the accident. If your state allows, you would spring the additional cost on the adjuster prior to taking delivery on the repaired unit. You would not mention this until that point.
3) If you had non refundable reservations for a campsite you won't be using, you need to add that to the claim and provide the adjuster with proof of your reservation fee and that it was non refundable.
I'm going through something similar on our tow vehicle right now. Bought the vehicle specifically for towing capabilities and after the accident were without that capability. Other insurance must restore us to pre-loss condition as close as possible. They are providing a rental tow vehicle with all necessary hookups, etc. They said they wouldn't at first, but I wrote them a lengthy email explaining why they should. Now they are providing one. Took a little research on my end finding a rental vehicle that was equipped.
As far as the diminished value, I am an insurance agent. I didn't even know about this, nor anyone in my office. I was talking to the head of claims for one of our companies and he told me about it. I don't know all of the details on how a diminished value claim is handled at this point, but my guy supplying the info is walking me through it and I'll let you know how it turns out and how to do it.
Bottom line, insurance is supposed to compensate you for what you've lost, even in the short term as long as it's possible and reasonable.
Also, I'm not here to solicit and I have not been involved in personal insurance in years, but I can offer basic advice if you have questions. Depending on which state you live in I may or may not be able to give you much advice!