You are very fortunate it was not more serious. Truly Someone was watching out for you! You are correct, when it comes to our RV 'rigs' we should never become complacent. (like turning your back on a baby in the bathtub).
Sorry for your expense, but am glad nothing serious happened to your arm.
For what it's worth .... I hit a mail box with my dully a couple weeks ago. Been driving dullys for years. Just got a little complacent there. We're with Allstate. Damage to my fat fender is $1400. Decided to go ahead and claim it since we have the vanishing deductible and it's now a zero deductible and accident forgiveness. Truck is in the shop right now, should get it back tomorrow.
Lesson learned ... you have experience now to share with others!
FYI, I see you are from Iowa. My daughter and family live in Hubbard near and Iowa Falls, Ames, Webster City. No clue where you are, just wondering. Say "HI" if you're passing nearby on Highway 20! :)