30 amp MH in a 50 amp CG
prndl....... Congrats on your new Thor!! Many pleasant miles ahead.
And welcome to iRV2. This is the place for...... whatever you need!
As to your plug in-- you'll be fine just as you are. That thing you have (referred to as a "dog bone") will enable you to plug your 30A cord into a 50A socket. You may not even need it, as most CGs that bill themselves as "all 50A" actually provide each campsite with each type of receptacle, one 30A and one 50A, to handle just such a situation as you have.
As to protecting your coach, your Progressive unit will do the job just fine. When you plug your 30A coach into a 50A line, your coach will still only draw whatever electrical power it needs. There will still be the higher amp capacity available from the system, but nothing in the normal setup will try to cram 50A down your throat.
Enjoy your trip!
John & Diane, Fulltimers. RVM103 NHSO
On the road since June '12 with Lincoln, the guard cat.
2002 Dutch Star 40, Freightliner, Cat 3126, 2004 Element