Hello, I am not sure about 62/180 to the East of Seminole but certainly from Hobbs to the Caverns it is very good. I commute between the Hobbs area and El Paso at least 2x a month and the road is very good with minimal truck traffic.
However, going through Carlsbad things are just crowded, there are so many people there it can be very busy on the roads.
I do not have first hand experience with hwy 285 but do believe that you will find it very busy with oilfield truck traffic which does have a tendency to tear up the roads.
Not sure of your proposed route but you might consider I-10 to Van Horn and then head North and pick up 62/180 just downhill from the Guadalupe mountains and then go up to the caverns. Stopping at Guadalupe Mountains NP Visitor center should be included in your plans if you have never been this way.
As far as overnight stops - the RV parks in Carlsbad are all extremely full of oilfield workers so finding a spot there may be difficult. The KOA to the North of town seems like a nice place and is often recommended for visitors. It's a long drive to the caverns but there may be little choice. If you can go without hookups, there is a small RV area at Guadalupe Mtn NP.
Hope this helps at least a little. Feel free to PM me if you have specific questions.
Terry