Six ways of adding a SATA drive.
In June 2019 I heard from Wes who had added a 120GB SSD to his t5740 without any hassle. He'd bought a Sandisk SSD and disassembled it - removing the 2.5" housing to leave the basic circuit board and connector. (See this article for an explanation).
Like Glenn he'd used a right angle SATA adapter so that he could mount it parallel to the motherboard in the t5740.
Checking on eBay.co.uk I see these are about £3 delivered.
The photo below shows it in place on the motherboard. It just fits - any longer and it would clash with the large capacitor.
Any comments? email me. Added June 2019