You don't want to share hydraulic or vacuum systems between your TV and your trailer.
If you have vacuum activated hydraulic trailer brakes, you would want a vacuum pump on the trailer to activate your trailer brakes. Then you would control that vacuum pump for trailer brake opperation.
Connecting TV engine vacuum to the trailer brake system would invite total brake failure should there be an issue in one of the systems like a leak. If the systems are isolated (trailer from TV) then a failure in one system means you have limited brake opperation however not a total loss.
What I think you are saying you have is -
A TV that uses hydraulic pressure from the PS pump to boost brake operations
A trailer that uses a vacuum signal to control hydraulic disc brake operation.
Airstream used a hydraulic brake system on some units more as an option over electric brakes. The durability was not the same as electric brakes from what I know. Conversion to electric trailer brakes would be spendy the short run and EZ to fix in the long run. (or out on the road) This decision is going to be based on how much you move the trailer and exposure to breakdowns. Likely you could find parts locally to make the trailer brake conversion to electric as this is very common. (Loaded backing plates and drums with some wiring to a trailer connector) The hydraulic brakes are uncommon and locating parts for repair will have it's issues.
1966 Mercury Park Lane 4 DR Breezeway 410 4V, C-6, 2.80 - Streamless.
1966 Lincoln 4 door Convertible 462 4V 1971 Ford LTD Convertible 429 4V Phoenix ~ Yeah it's hot however it's a dry heat!