HOBs are tempermental as is. i would hesitate shutting it down for any length of time because the slime coat may partially dry out inside and have to re-establish. it probably wont skim well having to readjust each time it fires back up.
here's a cheaper solenoid valve if you venture to try one
Our PSL-15 line of Engineered Nylon Plastic electric solenoid valves are 1/2” semi-direct lift valves operating from a normally closed position. The PSL-15 has a 1/2” female NPT threaded port. It can handle media with a CST of 20 or below and has a flow rate of 4.8Cv (Appx 36 GPM @ 60 PSI)...
www.electricsolenoidvalves.com
only thing else would be to mod it which would void the warranty (aqualifter pump on timer pulling from the top of the intake tube)
maybe someone else here has tried something similar to what you are suggesting and had good results.