Welcome to the world of Lippert - the world of PARANOIA!
As stated - you most likely will be stronger than factory after the Mod so I wouldn't worry too much about the pin box anymore, but as stated, you still have a world of spring hanger and I-beam webbing cracks to worry about in the other places Lippert made shortcuts.
I wouldn't jump through a lot of cash to try and upgrade to air-ride either. Had a friend that swore by the expensive trailersaver air hitch he installed when his 5er was new - and it wasn't too many years before he was repairing the front frame as well after a catastrophic weld failures that did some pretty severe damage to the inside of the rig.
My opinion - bend over and get it fixed and hope it stays together for the rest of your journeys.
I've pulled Lippert trailers since 04. First trailer never broke but the welding looked like beginning AG class. Second unit came with Mor ride partial suspension. At factory axles and shackles were not placed correctly. Fleetwood, called me and told me to take my unit quickly to dealer and it would be repaired. Lippert sent man, but he only relocated one of the axles. No knowing this I ran unit about 2 years and saw problems. Dealer contacted Lippert, and no help. It is now fixed properly thanks to a good dealer, and Mor Ride sending the correct parts and showing exactly where it all should be welded. Traded the unit off, and bought Cameo. Sorry Carriage went under, but at least I now have a quality product.
Hopefully Lippert will do you better then they did me.
kenneth wooster- retired farmer. Biblical History Teacher in public HS, and substitute teacher.
wife Diana-adult probation officer, now retired.
31KSLS Full Body paint Cameo
Ford F350 2014 DRW 4X4 King Ranch.
20K B&W Puck mount hitch
Why not answer the OP question instead of bash the frame maker or other folks which leads to another closed thread.
My current '97 5ers frame around its pin box support gave way in '03. The dealer dropped the bottom close out skin and added bracing per my instructions and their tech folks/weldor, probably much like Lippert will do.
My 5ers frame around the pin box support is now much stronger/better engineered than OEM. No issues since '03.
"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers
'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach
'97 Park Avanue 28' 5er 11200 two slides
The only complaints I've seen about weak or broken pinbox attachments have been related to Lippert frames (that's a fact). To JIMNLIN, it's difficult to discuss how to fix the OPs initial query without bring Lippert in, and I don't believe it's "bashing" in this case. I have one, and on inspection, the welds appear to be poor although I have not had a problem with my 2002 unit (and that's a fact, too).
Now, having said that, to the OP, did you have a gooseneck attachment on your trailer? If so, you really need to go back to a standard FW.
I think that Lippert, having a "repair kit" on hand, says a lot. Also, Lippert appears (not a known fact to me) to have a traveling welder available to fix their problems. I think also that your pinbox attachment will be stronger and I would not hesitate to continue to use the trailer for its intended use. But, I would also find someone expert in frame inspection to take a look at the entire frame for other failure points, and especially the spring and bumper mounts, and get those taken care of post haste. I'd also speak with Heartland directly to see if they can assist, even though the unit's out of warranty. Lastly, once the unit is fixed, I wouldn't invest in a Mor-Ryde of other hitch of its type unless you detected a reason for one prior to having the pinbox problem; wasted money IMHO. Please let us know how it all works out for you.
2014 Forest River Wildcat FW 327CK; 2005 Ford F350 Lariat Crewcab 6.0, 4x4, 3.73 rear. Retired and enjoying life