Adam,
There are two different issues in your question. Frist, the OEM plastic surge tank on your coach was from a Ford truck application, and it is very prone to failures from cracking when used with the 13 PSI radiator cap that your coach was originally equipped with. So after 2 tank failures in 3 years, about 12 years ago, I changed my 2000 Marquis to a 7 PSI cap since the coach never ran above 200 degrees and I saw no need for the higher pressure cap. After installation of the 7 PSI radiator cap, I never had another tank failure. When I traded the Marquis for the Solitaire that I drive now, the radiator cap change was the first thing I did to the coach because the Ford tanks are no longer available, and if you have a tank failure, you will have to purchase one of the metal replacement tanks that are now available.
I installed the recovery tank a few years later. The main reason for the recovery tank was to be able to see the coolant level at all times, hot or cold without removing the radiator cap. The surge tank was not transparent enough to check the coolant level and on the 2000 Marquis there is little room above the surge tank to check or add coolant. Coolant recovery bottles are readily available, and they are an easy addition to your cooling system. However, you will need about a 3 or4 quart recovery bottle since your coach has such a large coolant volume. So if you use a standard automotive bottle you will probably need to mount 2 side by side so that they fill evenly or you can do like I did on the Marquis and use a transparent gallon bottle an make your on bracket.
Gerald