3-4 space bike rack

We just picked up our new Zinger 32QB!

I have a 2012 sunset trail 30 RE I install a 2" bolt on hitch cost $40.00 reinforce the bumper with 2 L shape bracket, have no problem with the 4 bike rack

Many years, No issues. 
1-1/4" receiver (home made)  You can buy them.
Purchased bike rack at yard sale.  I forget the brand of it, It is old. Seen similar ones at walmart.

I would love to see pictures of failed bike racks? Or claimed bikes swaying in the wind. I have never seen it. Searched the web everywhere. Everyone has a cell phone and if this was a big problem you would find pictures all over the web. All you read are claims (what if/ It could). I had an rv bumper welds crack and i didn't have anything mounted on it.. The only way i noticed it was i climbed up on the bumper to clean the window and i heard the creaking.  Upon looking closely at the welds the bumper was tearing and were fractured.. I grabbed the welder and fixed it up. This was definitely not a bike rack problem. I had nothing on the bumper. Not a spare and I didn't have my bike rack at that time.

My 4 135lbs bikes bouncing + 5 for the receiver, 10 for the bike rack, tearing out welds and ripping 4" .062 tubing,  WOW..  Has to be more to it..   My ubolts are rated for 1,000's . My welds will not rip out..  I inspect he bumpers weld yearly from my first rv's bumper issue.  So i am 180lbs, Go jumping on the bumper (real hard)  i can brake out the welds?  Will the weld fractures be quicker if my wife helps me? I climbed up on my bike rack and started bouncing. The bumper didn't move, although the bike rack itself flexed. 

Would love to read about damages and injuries from others due to bumper failures or bikes on bumper problems. Links?  Also more info on bumper, bracket failures also please. I don't want to hurt anyone so i am curious if this is a problem. I am sure there are millions of people out there with my similar setup.  Would like to research it before I go through the effort and money to mount a class 3 hitch(no bumper interaction) for 4 bicycles.  If a bike weighs 50lbs. Its time for a new bike. Bikes don't weigh 50lbs !.

Bike Rack options for the OP. My dealer told me it was fine with the bumper adapters for 3 bikes, 4 max, You can talk to you dealer, Or stop in at any dealer close to your home..
http://www.campingworld.com/shopping/item/rv-4-bumper-adapter/17221
http://www.campingworld.com/shopping/product/trailhead-bike-racks/7711

Bit cheaper. But use ball bungies in conjunction with the carriers straps to hold bikes securely.  I use about 6 ball bungees when all bikes are on there. 
http://www.walmart.com/ip/Deluxe-4-Bike-Carrier-for-2-Hitch/10812001

Bumper adapter, Also sold at your RV dealers. In my dealer's book it is P/n 92-1830 31-24
Also sold here
http://tweetys.com/rv-bumper-receiver-adapter.aspx

I  was thinking of a rack on the back of the new unit but am now second guessing that. I think the smaller bikes (X2) should fit nice into the pack and play side door. Likely make a better bike rack in the bed of the pickup for the full size bikes. (X2).
Forums are great for helping make a decision.