First off, congrats on the new addition to the family!
As far as the cover, I place one over mine during the winter months with no issues... I will say that where my RV is in the back yard, I don't get much wind because of the trees around us and winters aren't real rough here in Virginia for the most part. In the process of buying the cover, I took a tip to tip physical measurment on the 5th wheel and then I ordered the cover closest to that measurment. My actual exterior lenght was 37 & 8" so I bought a 38' cover. I do prep my RV for the cover... wash it first, turn down the radio ant; wrap any and all gutters sticking out with pipe insulation as they will work their way thru the cover after one season otherwise... Ensure the cover is snug after installing it so it moves as little as possible. With all that done, I have had good luck with no problems so far.