Good luck w/ your boat.
It may seem counter intuitive, but in many ways a larger boat is much easier to handle. Two engines, spaced far apart w/ large propellers make low-speed turning and tight maneuvering much more responsive.
Take a Power Squadron or USCG Boater Safety Course. Do it as a family activity.
Get and read a recent copy of Chapman Piloting. Then read it again.
Don't yell, have fun and most important, ensure the wife is fully capable of handling the boat. My wife has ZERO excuse to dispose of me at sea, then bat her eyelashes and claim she was not capable of saving her incapacitated husband.
IMO the person responsible for handling the boat should abstain from alcohol until the boat is tied up for the day. There is waaay too much responsibility and waaay too many things that can go wrong. Almost every boating problem is alcohol related.
Get a towing service, like Sea Tow or Boat US. Any broken-down tow back will be over $1K, so the annual service is well worth the cost.
After I learned how to handle my 2000 380DA we would practice w/ the wife docking the boat into an empty marina. She can dock as-well (or better) than any guy.
Don't be discouraged when upcoming repairs are quoted at a higher cost than was paid for the boat, that may be the time to move on.
The Mercury engine service manual may be purchased from many locations, new or used. What is the engine?
The Sea Ray manuals are available on-line, on this site.
https://ownersclub.searay.com/sroc/SROC_Tech_Resources?feedtype=POPULAR&dc=All&criteria=ALLQUESTIONS#show-documentation
Enter: 1987 Seville into the search bar.
Is your boat the Cuddy Cabin, Closed Bow or Bow Rider?
IMO, the most important Sea Ray document is the Wiring Diagram. If that isn't found on that site, then submit an inquiry to Sea Ray, because lots and lots of documents were made unavailable when they switched to this site.
Any competent canvas shop can fabricate the requested covers. Seek local recommendations to have the best option for success.
IMO the ONLY way to not fully drain the bank account (for normal people) is to attain proper mechanical skills, the proper tools, the proper documentation (including the ABYC manuals) and do-it-yourself. I have rebuilt every system on my boat and upgraded many systems to be at-least as-good as when it left the factory.