OK, I am very much looking forward to my trip to LAS this week thanks to the BD fare sale

Of course, I was hit by the well known problem of not being able to book a through-fare in Business from LHR so I had to book MAN-LAS-MAN as one PNR then LHR-MAN-LHR as a second (it's a disgrace, what does BD have against us poor London pax? Welcome to Manchester Airways, etc., etc.

).
I am flying up to MAN the night before so that's less of a worry but on the return I'm flying back down to LHR the same morning. I have a connection (all being well) of 3hr 10mins.
I have no experience of connecting at MAN or of BD's approach to hand baggage in these situations (I've normally either checked bags in or just had short trips, small bags, etc.). What I do know is, BD will not through-check bags on separate PNRs any more which is a problem for the return.
If this were a BA trip (i.e. in my comfort zone

) I know I could use my Samsonite hardshell rollercase which fits the maximum BAA dimensions and not worry - I can easily fit for clothes for 4 days, the stupid plastic bag and my laptop + some connectors in there.
As far as I can tell, BD's size guidelines are the same as BA (i.e. up to the BAA maximium). But they have weight restrictions which BA don't any more. I wouldn't worry about checking it on the way up given I'm overnighting, but on the way back, I'd have to go landside, reclaim, re-check, re-clear security. This is what bugs me - the connection time should be fine for all this (even on a Monday morning), but what a PITA (I'd rather just go to the lounge and get a shower and some breakfast).
What do the experts reckon? I can do it all as hand luggage? Any other tips re connecting at MAN, etc. would be appreciated too (I've searched for the luggage stuff, am just about to search for MAN tips) in case I lose control and buy stuff in LAS and end up having to check the case anyway. TIA!