First off, there are CTOL airplanes which can deliver replacement engines to aircraft, just not F-35 replacement engines (because of their large blade diameter). USN had previously used C-2 Greyhounds for these sorts of duties, but they have too small a fuselage, and were being decommissioned. There was talk of converting some decommissioned S-3B for COD, exchanging their fuselage for a wider one to accommodate the F135, but this was not pursued. https://archive.ph/20150209193642/http://www.defensenews.com...
Second, lots of helicopters can carry F-35 replacement engines, including the Boeing Sea Knight. https://en.wikipedia.org/wiki/Boeing_Vertol_CH-46_Sea_Knight I believe that the USN didn't want to depend on conventional helicopters because of their relatively short range.