This really isn't as big a deal as everyone makes it.
#1 Just weigh the airplane. Fuel drained and sumped is the best way. There is "headspace" in each fuel tank and aircraft weigh heavy when the fuel tanks are topped off vs weighing drained and sumped.
#2 You should be able to get the factory equipment list from Cessna. If not, ask around on the forums and hopefully someone with the same year airplane can give you a copy of theirs to use as a guide in making a new one for yourself.
(Equipment Lists in heavy private aircraft are typically a mess because often they don't have just one book that holds the ORIGINALS, so there are a few books containing both copies and originals and if one book gets updated the others may or may not.
Its a huge PITA!!!!)
My advice to all customers, is keep the originals in a binder with logbooks. Keep copies of them in the airplane.
Make a binder to keep things organized in the airplane. You can throw the originals on a copy machine to reduce the size to about 63% and they will fit into a half-sheet binder with no problem. That binder will fit in all the glove boxes I've tried.
In this case I bought a brand new 205 owners manual (from Cessna $40) and was pleasantly surprised to see the plastic spiral binding. I removed the binding, three-hole punched it then re-installed the binding. Now it can be added to the three ringed binder.
If you have FAA approved supplements, like an Aspen, I would try to get a pdf color copy from Aspen then print it two sided color on a laser printer at 63% to 67% size to fit this binder. I use at least 24# paper as 20# is just too cheap and not durable.
An example of trying to catch up the equipment list: