Pump Options for Sink Water Pressure

Hi all! I'm early in the process of converting an enclosed cargo trailer to a small camper (travel trailer.) It's 6'x12'. I'm not to this point yet, but I'm trying to figure out my water options when not hooked to a campgrounds connections. I found a good fresh water tank on etrailer.com and I've seen a manual sink pump made by Valterra, but I'd rather have the ability to pump and build pressure up and have a continuous stream of water. Not only for the sink but also for a shower wand I would put out back (not planning to use soap, etc... just use it to rinse off) accessible when the back doors are open.

Any suggestions for what I could do? Foot pump is fine if there's a way to do that. I do plan to put a small grey water tank under the inside sink.