No you're not crazy! We've done it a couple of times in 2014 and 2016 and it's fabulous.
It's a lot of flying but if you organise it well it can work. We did Manchester - Heathrow and stayed overnight. Heathrow to LA and then six nights at the
Disneyland hotel. We then flew down to Orlando and stayed 10 nights and then straight back to Manchester. I booked the USA flights with VA, the shuttle to Heathrow with BA and the LA to Orlando with Delta.
We opted for six nights in LA both times as we wanted to see a little of the local area too and we had a couple of trips planned. We did the usual touristy stuff to Hollywood Boulevard etc and up into the Hollywood hills and also a trip to Santa Monica and Venice Beach. I wasn't the greatest fan of LA itself as it's so sprawling but there's so much to see on the outskirts.
Disneyland is fabulous and you need four days to see the two parks. If you want any help in planning just give me a shout.