wing here's a simple solution. Get a VHF (covering both VHF HI&LO) antenna and a cm7777 preamp. The Delhi VIP-302SR must still be available locally. You could choose another model that cover the whole VHF range like this one.
Point the VHF antenna to CF, keep your 4228 the way it was. Set your cm7777 to separate inputs with the FM trap ON(IN) and connect both antennas to the preamp. You are done. Your big job is to figure if you have room for the VHF antenna on your current mount and around it, if clearance is good for both plus some place to put the preamp.
Personnally when I connected my VIP-302SR in the attic (pointed to CF) I got way better Global & CTV than I ever had coming off the back of my 4228hd on the roof. Your results may vary, but a preamped VHF antenna on the roof should be OK to pick up Global. backpackster in Navan picks it up on a roof mounted preamped VHF antenna.
The 302sr has a gain of 4 vs the 526 which has a gain of 4.9 on VHF Lo. But the 526 isn't even rated for VHF Hi, where the 302sr has a very respectable gain of 8. It's a smaller antenna than some of these big monsters, but still big enough at about 9 feet on the biggest end.