I have an excellent C5+ single fork mount with RA and DEC drive, table top wedge fitted with $250 JMI optical encoders which I think will also work on a C8 fork mount. I am using the ota for another purpose. The tracking is very precise and it would work great with one of the Orion Maks or ETX. The dovetail slot with the quick release on the fork arm is 3.75" long and is v shaped being 1.5" wide at the top and 1.75" wide at the bottom. Looks like it would be very close to accomodating a GP dovetail plate. No tripod. $450.
As far as trades see my ad for the Vixen BT80