Can a caretaker manager contract with no milestones live outside IR35?

I am currently working directly for a client who wants to offer me a new contract for a year with no specific milestones or tasks of work

For the last 2.5 years I have worked directly for a client on projects that had detailed tasks and milestones with payments on completion of each milestone, separate contracts for each project for which I had to quote a price which was thereafter fixed. For most of these contracts I have worked offsite, attending when I deemed necessary.

Having recently lost their Network Manager, they have asked me if I would consider a year long contract as a 'caretaker manager' until they decide on how they want to proceed with post, outsource or otherwise etc. My role will essentially be to support the internal network; managing and rectifying problems as they occur, carry out equipment/software upgrades as necessary. I will be my own boss determining what is to be done and when. They have a permanent IT Support person, he will not be under my control but may on occasion carry out tasks for which I will specify the details. Attendance on site will be at my discretion, though given the task, I expect to be in attendance probably 70% of the time.

Can this type of contract live outside IR35 - or will I be liable due in part to the non-specific nature of the contract and that I have been contracting with them for some 2.5 years (albeit with short breaks and one contract elsewhere)?

-- andymiros