I moonlight on the side for 2 business, I made them vary aware of what all my limitations would be since I have a full-time job. I have helped both of them move into new locations since then. It took alot of after hours work and planning to make sure they knew exactly what was needed to be communicated to the contractors hired to do the cabling etc.
I feel as long as you and them are fully aware of the limitations and are fine with them go for it.