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Yeah, I know the right answer is buy the right components, but I'm wondering if the addition of a cheap bit of metal will help me get this build done at lowest cost. If the answer is a resounding no, I'll be on the look out for cheap EA mechs.
Scrabble-
It depends on your bike. Moving the mech down 1.6cm will get you ~4 extra teeth. So if you think it's already maxed out on a 28 you should be safe to go up to 32 with the roadlink. If you think it could clear a 32 then you can go up to a 36 with a roadlink. I don't know the dimensions of a roadlink but if it's more than 1.6cm between the centres of the bolts you get more teeth.
You don't need to worry about wrap with 1×, your mech can already wrap anything up to (50-34) + (28-11) which means an 11-44 in a 1× system.
If you can borrow a couple of cassettes and buy/borrow a roadlink that's the best way to find out.
frankenbike
Get a sram exact actuation mtb mech, my setup is apex shifters, X5 10 speed mech with a 36t cassette and is sweet.