Wait until HIS insurance company gets in touch with you before you spend too much time trying to find parts, etc. That is the job of his insurance company, assuming he is the one that is at fault and charged.
If it gets to that point when they ask what you would like to do, remind them of the diminished value of a repaired vehicle with CarFax damage.
Just be polite and firm in your demands to be compensated to exactly where you were before the accident. You may also remind them of the additional expenses you incurred because of the accident and the lost time you will have from travels until you have an RV again. Give some real world numbers etc.
Do not threaten any legal action at all. If the man's insurance company will not work with you to your satisfaction, then you contact your insurance company to pressure them on your behalf.