What TDEE tool for ME - HRM, fitbit etc?

I know this has been covered a lot, but I haven't really worked it out myself.

In May I was 225lb, now a smidge under 175b I reckon. Ideally I want to get to 161lb, which would be around 10% BF, then start making a good effort to bulk up a bit (yes, I'm a tart and would like some definition in my abs thus a quite low BF target ).

As my lifestyle can vary a fair bit, it'd be nice to get a better idea of exactly what's going on.
Unfortunately it tends to be a bit variable - at work I'm often shifting heavy stuff around. For instance carrying car gear boxes up stairs can't have hurt my recent weight loss! However, other days can be pretty sedentary. Currently got MFP set to fourth out of five levels - hopefully as it's set to a 1k calorie deficit, worst I'll do is just be a bit lower than that on slower days.
I've been doing a bit of indoor rock climbing recently. When I get a bike I'm happy to ride around town (rather than my expensive mountain bike), hope to be using that daily. I expect the non-HRM tools may have some trouble with this sort of exercise? Dog walks every day too.
Not sure how well a HRM monitor does either - generally climbing I wouldn't expect to see a massively higher heart rate as say I would have seen at a spinning class. Some things I've read suggest that the monitors are more designed to be used for higher heart rate exercise.
Also, obviously I appreciate a heart rate monitor chest strap permanently attached may get annoying. Though, once I've got a reasonable idea of what's going, I'll be happy to just use details from previous days.
As I'm nearing the end of my fat-loss goals, I think it's going to be more important to make sure it's "done right".