I think a 4 string in B,E,A,D would work for most of what I play. Heck even D,E,A,D would work. I've used that tuning a ton, and on occasion, C,E,A,D for Cinderella's Diary of Jane if I can ever get anyone to play it, which is a rarity. It's always you wanna play it, you sing it, lol. Ain't happening.A 4 string in BEAD will work for a Modern Country band.
But I had the opportunity to pick up a Peavey Millenium BXP 5 for 200 bucks and I took it. And right now it's getting a lot of attention. Just a really fun bass to play. And I intend on getting my money's worth out of it
I was actually looking at modding it too. Have already talked to Nordstrand about a custom set of pups based on the NJ5 Vintage Single Coil that they make. Peavey for some odd reason made a 5 string bass with a 4 string pup sizing and no exposed poles. Probably more economical because they could use the same pups in the 4 and 5 string models of the same bass. But finding a true 5 string replacement pup for it hasn't been an easy task. Don't know if I'll go that route yet or not as I'll end up with more money in the pups than I have in the bass.
The reason I even considered upgrading pups was I was having an issue with the pots or possibly the pups, or so I thought I was anyway. But two things fixed that issue. First one was if you're going to run the bass straight to the board make sure you have Hi Z engaged. Clearly a user error on my part. And second, clean the pots. Wonders never cease

The pups in it now are pretty good, and the tone is quite good actually. I'm now in one of those "if it's not broke, don't fix it" conundrums. How much would buying the custom Nordstrands really do for the tone? Probably not enough to justify doubling what I already have in the bass and then some. I've even recorded it with it already and it sounds fantastic in the mix. The Nordstrands should give it a little more growl on the low end. But it already has more growl on the low end than any of my other basses.