In that case, you should definitely give DD a look. Their FF rails mount and dismount fairly easily which would allow for easier maintenance. They even have 2pc Freefloats to offer with 3 different mounting options. Mounting is solid too, esp on their Lite and RIS II rails, as they have their own proprietary anti-rotational systems.
That said, I recommend the M4A1 RIS II. Long enough for your needs , is 2 pc and probably the most solid mounting system amog all their rails from what I can see off their website. -- it has locking nubs at the rear of the mounting ring which prevent rotation on top of the protruding screws. -- someone please correct me if this feature is also offered on Lite Rails.
https://www.danieldefense.com/?page=...&product_id=17