I'm no Electrician so I can only speak from experience. As to using an RV Power Converter for your purposes, again, I can't speak from that. Hence, obviously, if you get no answer on the Forum, how 'bout visiting an RV Shop for information. My 'gut' says that you shouldn't have a problem but my gut isn't any part of the Scientific Method ...
ANYWAYS, the key is to be sure you have the proper Voltage at the END of the run. There are formulas that you need to use to figure out the length and type of wire you need for the job. You see, the longer the wire-run, the more power loss you have. Therefore, if it turns out that your converter won't power up what you're looking to power up, you need to either change the wattage, shorten the run, or some combination of both.
You make mention of "four different power supplies". Does this mean you have 4 'plugs' to use off of the converter??? If so, what I've already said still remains true. The GUAGE of the wire, its length, and the amout of wattage need to be figured out whether or not you use 1 plug (for your plans), or 4 plugs. In short, you may find you've maxed-out your converter with just the 35 walkway lights. If you add up your wattage, you have 35x9=315 watts PLUS 35x4=140 watts. That's a total of 455 watts. IF you know the output of your RV Converter, you'll know (from the outset, what you can do.
In closing, I'll make a suggestion. What you probably don't realize is that the normal human eye can 'adjust' to the lack of lighting fairly easily, and fairly quickly. I have 2 walkway lights (lighting up 20' of flat concrete sidwalk) totaling 14 watts. Yup, 14 watts. AND, that's MORE than I need. Look at the various light fixtures to see which will do the best job of lighting up the walkway. One of my mushroom lights at 7 watts will safely light up 30' of walkway (15' on either side of the light.) Obviously, the closer to the ground the light is, the more lights you will need. In addition, I have 4 4-watt in-step lights lighting up 10 concrete steps in the front of the house. The 1st, 4th, 7th, and 10th step each have a light built right into the 'face' of the step. Really, you don't need a light in every step or even every other step. You see, the theory is to let the human eye 'adjust' to the dark, and then 'help' it with just enough light so that as the eye goes from lighted-step-to-dark-step, it isn't continually trying to 'adjust' to the lighted and darkend 'conditions'. That's why if you put too much light out there, someone could actually get hurt when the eye goes from light to dark. (I thought I was done ...) Our deck has 11 4-watt in-post lights. That's a total of 44 watts lighting up a 12' x 30' deck (360 sq. ft.). After about 2 or 3 minutes, our eyes adjust just fine to the lighting. In fact, we turn off the inside light(s) closest to the doorway going out to the deck because IT becomes distracting! AND, again, going from the outside to the inside, your eyes are already adjusted for a minute or 2 to the darkened outside. Yup, it's the same principle as waking up in the middle of the night and turing on the bathroom light. You can go blind! And if I'm not mistaken, those nightlights are only 4 watts too.
I do wish you well. MY best to ya and hope this helps.
Jay J -Moderator
PS: Thanks for listening to my 'winded' speech ... PPS: I guess my last point is you can help 'maximize' your converter by cutting down you the wattage and/or the number of lights ... PPPS: A lighting store or landscape store that sells Landscape Lighting has brochures with the 'equations' inside them to figure out what you need in terms of wattage and wire length and wire guage ...