10s rear derailleur options.

I need to replace the 105 5700 Gs rear mech on Jamis Aurora elite tourer/gravel/commuter. Currently also running 10s Shimano bar end shifters (DA I think) and Shimano triple crankset 50/39/30.

I'm hoping that I can replace it with something that can handle a wider range cassette for when I have a touring load (up to 36 or even 42) and something more modest the rest of the time (28 or 32). So I could have one rear mech but keep two chain and cassette options that I can swap between as required.

Spent sometime looking into this with inconclusive results, has anyone done this, is it possible, is it a good idea? Many thanks in advance and apols if posted in the wrong place.

Fit a 9 speed mtb derailleur like xt medium cage or long cage.

Sounds promising, would that still play ball with 10 speed set up ?

Yes. Shimano MTB up to 9 speed works with road stuff up to 10 speed (excluding Tiagra 4700 and 8 speed Dura Ace I think).

I have a 9sp Deore that worked great with my 10sp 105 shifters and a 36t cassette. With a really long b screw from the hardware store you ought to be able to get the derailleur to go around more than 36 teeth.

Thanks all, I shall give this a try.

you could of course stick with the standard 10 speed derailleur and use one of these
https://www.sjscycles.co.uk/gear-spares/aluminum-rear-derailleur-hanger-extender/

Is this any 9 speed shimano rear mech (inc Mega 9), and does this work with road flat bar shifters as well?

I don't see a reason why it shouldn't work with Mega 9 stuff, never paid attention to that myself though. Sure, it works with flat bar shifters as well, as long as it's not a 4700 shifter.

That’s similar to the setup I have: 9sp XT MTB rear mech, 11-34 10 speed cassette, DA 10sp bar end shifters, 28-39-48 triple crankset. All work fine together. The cranks and front mech are Campag but that’s another story and makes no difference.