Welcome, I love the Miramar.
IMO most of the Thor Gas Motorcoaches are very simular. So if you read a lot of post about the "Instant Hot water tanks" .... it will most likley apply to all RV with similar HWT. Or issues with "loose trim, screws falling out" etc. Just expect that as well.
The engine and Chassis all seem solid on all models so I think your safe with that part. Ford does a good job with them.
Check for signs of water leaks! Inside and out. Inspect the roof looking for bad caulk, rips or tears etc. Run the slides out, awning, etc.
Spend at least 2 hours looking over the rig, take pictures, go on line and ask question before you put down a deposit.
Do your research. Check every little detail of the RV BEFORE you purchase (because you will always overlook something... hopefully it will be minor).
And what ever they are asking offer them like $20 K less (no joke). Most likely you will get $10K off. You can use that money to repair and customize your RV. If its a dealer... be prepared to walk out the door. I bet They wont let you .... so then you know you have the upper hand.
Keep in mind that many RV's are sold new with 30% to 40% off of list price. So a new $150K RV on the window sticker could be purchased for like $90k back in 2017. So if the 2017 is advertzied for $90 or $100 IMO thats TOO MUCH (Imo).
(I dont know the list prices im just giving you examples)
So this used 2017 Mirimar Needs to be like $75?? Not sure on $$ but much less than the best deal one can get on a brand new model.
Just take your time and ask lots of question.